WO2010067902A1

WO2010067902A1 - Resin composition for filaments

Info

Publication number: WO2010067902A1
Application number: PCT/JP2009/071072
Authority: WO
Inventors: Susumu Ejiri
Original assignee: Sumitomo Chemical Company, Limited
Priority date: 2008-12-12
Filing date: 2009-12-11
Publication date: 2010-06-17
Also published as: JP5720093B2; AP3393A; JP2010159403A; CN102245817A; AP2011005775A0; CN102245817B

Abstract

A resin composition capable of providing filaments superior in bleeding performance of an insect-controlling agent in the initial stage of use thereof is disclosed. The present invention relates to a resin composition for filaments, comprising a high-density polyethylene, an insect-controlling agent and synthetic silica, wherein the density of the high-density polyethylene is from 935 to 965 kg/m³, and the MFR thereof, from 0.1 to 6 g/10 mins; wherein the average pore radius of the synthetic silica is from 0.040 to 0.105 m; and wherein said resin composition contains 100 parts by weight of the high-density polyethylene, and 0.1 to 10 parts by weight of the insect-controlling agent and 0.1 to 10 parts by weight of the synthetic silica per 100 parts by weight of the high-density polyethylene.

Description

DESCRIPTION

Resin Composition for Filaments Technical Field

The present invention relates to a resin composition for filaments, and filaments formed of the same resin composition. Background Art

Resin compositions which comprise polyolefin resins such as polypropylene and polyethylene, and insect- controlling agents are formed into a variety of molded articles for use as materials for preventing bugs such as ticks, lice, mosquitoes and flies. For example, Patent Publication 1 discloses a composition comprising a polypropylene resin and an insect-controlling agent, and a filament obtained by melt-spinning the same composition. Patent Publication 2 discloses a composition comprising a linear low-density polyethylene and an insect-controlling agent, and a collar made of the same composition. Patent Publication 3 discloses a resin composition for filaments, which comprises an ethylene-α-olefin copolymer and an insect-proofing agent. Patent Publication 4 discloses a resin composition for filaments, which comprises an ethylene homopolymer and an insect-proofing agent. Patent Publication 5 discloses a polymer composition comprising an olefin-based polymer, an insect-proofing agent and an insect-proofing agent carrier, and textiles made of such a polymer composition.

Patent Publication 1: JP-A-4-65509 Patent Publication 2: JP-A-6-315332 Patent Publication 3: JP-A-2008-031431 Patent Publication 4: JP-A-2008-031619 Patent Publication 5: JP-A-2008-106232 Disclosure of Invention

However, filaments made of the conventional resin compositions which comprise polyolefin resins and insect- controlling agents are demanded to be further improved in bleeding performance of the insect-controlling agents in the initial stage of use thereof.

Under such a situation, objects of the present invention are to provide a resin composition capable of providing a filament excellent in bleeding performance of an insect-controlling agent in the initial stage of use thereof, and to provide a filament made of the same resin composition. The present invention makes it possible to provide a resin composition for filaments, which contains a high- density polyethylene, an insect-controlling agent and synthetic silica, and which can provide filaments excellent in bleeding performance of the insect-controlling agent in the initial stage of use thereof, and filaments made of the same resin composition.

The present invention firstly relates to a resin composition for filaments, which comprises a high-density polyethylene, an insect-controlling agent and synthetic silica, wherein the density of the high-density polyethylene is from 935 to 965 kg/m³, and the MFR thereof, from 0.1 to 6 g/10 mins; wherein the average pore radius of the synthetic silica is from 0.040 to 0.105 μm; and wherein the resin composition contains 100 parts by weight of the high-density polyethylene, and 0.1 to 10 parts by weight of the insect-controlling agent and 0.1 to 10 parts by weight of the synthetic silica per 100 parts by weight of the high-density polyethylene.

The present invention secondly relates to a filament formed of the above-described resin composition. Best Mode for Carrying Out the Invention

The resin composition for filaments, of the present invention, contains a high-density polyethylene, an insect- controlling agent and synthetic silica, and this resin composition specifically contains 100 parts by weight of the high-density polyethylene, and 0.1 to 10 parts by weight of the insect-controlling agent and 0.1 to 10 parts by weight of the synthetic silica per 100 parts by weight of the high-density polyethylene. The content of the insect-controlling agent is from 0.1 to 10 parts by weight per 100 parts by weight of the high-density polyethylene.

The content of the insect-controlling agent is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, from the viewpoint of inhibition of stickiness of the resin composition before use in molding for filaments; and this content is preferably 0.5 part by weight or more, more preferably 1 part by weight or more, from the viewpoint of improvement on insect-proofing performance of the resin composition.

The content of the synthetic silica in the resin composition of the present invention is from 0.1 to 10 parts by weight per 100 parts by weight of the high-density polyethylene . The content of the synthetic silica is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, from the viewpoint of prevention of cutting of a filament, and this content is preferably 0.5 part by weight or more, more preferably 1 part by weight or more, from the viewpoint of inhibition of stickiness of the resin composition before use in molding for filaments.

The high-density polyethylene to be used in the present invention is an ethylene homopolymer or an ethylene-α-olefin copolymer. Preferably, the high-density polyethylene is an ethylene-α-olefin copolymer from the viewpoint of improvement on the strength of the resultant filament. Examples of the α-olefin include propylene, 1- butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 4-methyl- 1-pentene, 4-methyl-l-hexene, etc. Any of these monomers may be used alone, or at least two selected therefrom may be used in combination. The density of the high-density polyethylene is measured according to the procedure regulated in the method A out of the methods of JIS K7112- 1980, using a test piece which is annealed in accordance with the method for low-density polyethylene regulated in JIS K6760-1995.

The content of an ethylene-based monomer unit in the high-density polyethylene is usually from 90 to 100% by weight, based on the total weight (100% by weight) of the high-density polyethylene. The content of an α-olefin- based monomer unit in the high-density polyethylene is usually from 0.1 to 10% by weight, based on the total weight (100% by weight) of the high-density polyethylene.

Examples of the high-density polyethylene include an ethylene-propylene copolymer, an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-1- octene copolymer, an ethylene-1-butene-l-hexene copolymer, etc., among which an ethylene-propylene copolymer, an ethylene-1-butene copolymer and an ethylene-1-hexene copolymer are preferred. The melt flow rate (MFR) of the high-density polyethylene is from 0.1 to 6 g/10 mins. The MFR is preferably 0.3 g/10 mins. or more, more preferably 0.6 g/10 mins. or more, from the viewpoint of improvement on melt extrudability . Again, the MFR is preferably 4 g/10 mins. or less, more preferably 2 g/10 mins. or less, from the viewpoint of improvement on drawability under heating and mechanical strength. The MFR is measured at a temperature of 190°C under a load of 21.18 N, according to the method regulated in JIS K7210-1995.

The melt flow rate ratio (MFRR) of the high-density polyethylene is preferably 50 or less, more preferably 45 or less, still more preferably 40 or less, from the viewpoint of improvement on melt-spinning performance. Again, the MFRR is preferably 10 or more, more preferably 15 or more, still more preferably 20 or more, from the viewpoint of improvement on melt extrudability. The MFRR is a quotient found by the following division: that is, a melt flow rate (MFR-H, g/10 mins. in unit) measured at a temperature of 190°C under a load of 211.83 N according to the method regulated in JIS K7210-1995 is divided by a melt flow rate (MFR) measured at a temperature of 190°C under a load of 21.18 N according to the method regulated in JIS K7210-1995. The density of the high-density polyethylene is from 935 to 965 kg/m³. This density is preferably 960 kg/m³ or less, more preferably 955 kg/m³ or less, still more preferably 950 kg/m³ or less, from the viewpoint of improvement on drawability under heating. This density is preferably 940 kg/m³ or more, more preferably 945 kg/m³ or more, from the viewpoint of improvement on drawability under heating. The density of the high-density polyethylene is measured according to the procedure regulated in the method A out of the methods of JIS K7112- 1980, using a test piece which is annealed in accordance with the method for low-density polyethylene regulated in JIS K6760-1995.

As the method for producing the high-density polyethylene, there is employed any of the known methods such as solution polymerization, slurry polymerization, vapor phase polymerization, high-pressure ionic polymerization or the like, in the presence of any of the known catalysts for polymerization of olefin, such as a Ziegler-Natta catalyst, a chromium-based catalyst, a metallocene-based catalyst or the like. The polymerization may be either of batch process or continuous process, or otherwise may be of two- or multi-stage polymerization process .

As the Ziegler-Natta catalyst, there are exemplified the following catalysts (1) and (2) : (1) a catalyst which comprises an organometal compound as a co-catalyst and a component which is obtained by carrying, on a magnesium compound-based carrier, at least one selected from the group consisting of titanium trichloride, vanadium trichloride, titanium tetrachloride and titanium halo-alcoholate; and

(2) a catalyst which comprises a co-precipitate or an eutectic crystal of a magnesium compound and a titanium compound, and an organometal compound as a co-catalyst. As the chromium-based catalyst, there is exemplified a catalyst which comprises a component having a chromium compound carried on synthetic silica or synthetic silica alumina, and an organometal compound as a co-catalyst.

As the metallocene-based catalyst, there are exemplified the following catalysts (1) to (4) :

(1) a catalyst which comprises a component containing a transition metal compound having a group with a cyclopentadiene skeleton, and a component containing an almoxane compound; (2) a catalyst which comprises the above-described component containing a transition metal compound, and a component containing an ionic compound such as trityl borate, anilium borate or the like;

(3) a catalyst which comprises the above-described component containing a transition metal compound, the above-described component containing an ionic compound, and a component containing an organoaluminum compound; and (4) a catalyst obtained by carrying any of the above- described components on an inorganic particle-like carrier such as SiO_2/ AI2O3 or the like, or a particle-like polymer carrier of a polymer of an olefin such as ethylene, styrene or the like, or by impregnating the above-described carrier with any of the above-described components.

A production method using a Ziegler-Natta-based catalyst or a metallocene-based catalyst is preferable as the production method for the high-density polyethylene. A shorter residence time distribution during polymerization is preferable from the viewpoint of improvement on melt- spinning performance. To shorten the residence time distribution, a single-step polymerization, or a polymerization in association with parallel operation of a plurality of reactors in a process with the use of the plurality of reactors is preferable.

As the insect-controlling agent to be used in the present invention, there are exemplified compounds having insect-proofing activities, such as insecticides, insect growth-controlling agents and insect-repelling agents.

Examples of the insecticides include pyrethroid-based compounds, organophosphorus-based compounds, carbamate- based compounds, phenyl pyrazole-based compounds, etc. Examples of the pyrethroid-based compounds include permethrin, allethrin, d-allethrin, dd-allethrin, d- tetramethrin, prallethrin, d-phenothrin, d-resmethrin, empenthrin, fenvalerate, esfenvalerate, fenpropathrin, cyhalothrin, etofenprox, tralomethrin, esbiothrin, benfluthrin, terallethrin, deltamethrin, phenothrin, tefluthrin, bifenthrin, cyfluthrin, cypermethrin, α- cypermethrin, etc. Examples of the organophosphorus-based compounds include fenitrothion, dichlorovos, naled, fenthion, cyanophos, chlorpyrifos, diazinon, carcrofos, salithion, diazinon, etc. Examples of the carbamate-based compounds include methoxydiazon, propoxur, fenobucarb, carbaryl, etc. Examples of the phenyl pyrazole-based compound include fipronyl, etc. Examples of the insect growth-controlling agent include pyriproxfen, methoprene, hydroprene, diflubenzuron, cyromazine, phenoxycarb, lufenuron (CGA 184599), etc.

Examples of the insect-repelling agent include diethyl toluamide, dibutyl phthalate, etc. Any of these insect-controlling agents may be used alone, or two or more thereof may be used as a mixture. Otherwise, a compound which acts to enhance an insect- proofing activity may be used in combination with the insect-controlling agent. As such a compound, there are exemplified piperonyl butoxide, MGK264, octachlorodipropyl- ether, etc .

As the insect-controlling agent, an insecticide is preferable, and a pyrethroid-based compound is more preferable. In particular, a pyrethroid-based compound which shows a vapor pressure lower than 1 X 10^~6 mmHg at

25°C is still more preferable. As such a pyrethroid-based compound, there are exemplified pyriproxfen, resmethrin, permethrin, etc.

As the synthetic silica to be used in the present invention, silica synthesized by the precipitation method or the gel method is exemplified. Examples thereof include powdered silicic acid, fine powdered silicic acid, white carbon, etc. As the synthetic silica, amorphous synthetic silica is preferable. The average pore radius of the synthetic silica to be used in the present invention is from 0.040 to 0.105 μm. The upper limit of the average pore radius of the synthetic silica is preferably 0.090 μm or less, more preferably 0.080 μm or less, still more preferably 0.070 μm or less, from the viewpoint of improvement on bleeding performance of the insect-controlling agent in the initial stage of use thereof. The lower limit of the average pore radius of the synthetic silica is preferably 0.050 μm or more, more preferably 0.060 μm or more. The average pore radius is measured by the mercury intrusion technique. The specific surface area of the synthetic silica to be used in the present invention is preferably 240 m²/g or less, more preferably 210 m²/g or less, from the viewpoint of improvement on bleeding performance of the insect- controlling agent in the initial stage of use thereof. Again, it is preferably 50 m²/g or more, more preferably 80 m²/g or more, still more preferably 110 m²/g or more, from the viewpoint of improvement on bleeding performance of the insect-controlling agent in the initial stage of use thereof. The specific surface area is measured by the nitrogen adsorption BET method.

The oil absorption weight W (g/100 g) as the weight of the insect-controlling agent retained per 100 g of the synthetic silica is preferably 1,000 g/100 g or less, more preferably 500 g/100 g or less, still more preferably 350 g/100 g or less, from the viewpoint of improvement on bleeding performance of the insect-controlling agent in the initial stage of use thereof. Again, it is preferably 30 g/100 g or more, more preferably 60 g/100 g or more, still more preferably 120 g/100 g or more, from the viewpoint of improvement on retention of the insect-controlling agent.

The content of the insect-controlling agent in the resin composition of the present invention is preferably (5 X W) parts by weight or less, more preferably (3 X W) parts by weight or less, still more preferably (W) parts by weight or less, per 100 parts by weight of the synthetic silica, with the proviso that the oil absorption weight of the insect-controlling agent to the synthetic silica is W (g/100 g) . The resin composition of the present invention optionally may contain additives such as an antioxidant, an anti-blocking agent, a filler, a lubricant, an anti-static agent, a weathering agent, a pigment, a processability- improving agent and a metal soap; and a polymer component other than the high-density polyethylene. Two or more selected from the above additives and the above polymer component may be used in combination.

The resin composition of the present invention can be prepared by melting and kneading the high-density polyethylene, the insect-controlling agent and the synthetic silica, and optionally other components, according to a known method. For example, the high-density polyethylene, the insect-controlling agent and the synthetic silica are mixed in advance, and the resulting mixture is molten and kneaded, using an extruder, a roll molding machine, a kneader or the like; the high-density polyethylene, the insect-controlling agent and the synthetic silica are separately fed to an extruder, a roll molding machine or a kneader and then are molten and mixed; a mixture of the synthetic silica and the insect- controlling agent prepared in advance and the high-density polyethylene are fed to an extruder, a roll molding machine or a kneader and then are molten and mixed; and a mixture of the high-density polyethylene and the synthetic silica prepared in advance and the insect-controlling agent are separately fed to an extruder, a roll molding machine or a kneader and are then molten and kneaded. In case of the melt-kneading by the use of an extruder, the mixture may be charged from the midway of the extruder, using a side extruder or a feeder.

In the production of the resin composition, it is preferable to use the insect-controlling agent as an insect-controlling agent retainer which is prepared by retaining, carrying or incorporating the insect-controlling agent in the synthetic silica, or by infiltrating or injecting the insect-controlling agent in the synthetic silica, or by allowing the synthetic silica to adsorb or absorb the insect-controlling agent.

A master batch may be prepared by adding, to a resin, the insect-controlling agent or the silica, or the insect- controlling agent and the silica, or the above-described insect-controlling agent retainer, and the master batch thus obtained may be melted and kneaded with the high- density polyethylene, to obtain the resin composition of the present invention. Preferably, a master batch prepared by adding the insect-controlling agent retainer to the resin is used.

Examples of the resin as the base of the master batch include olefin-based resins such as ethylene-based resins, propylene-based resins, butene-based resins, 4-methyl-l- pentene-based resins, and modified, saponified and hydrogenated products of these resins, etc. Preferably used are ethylene-based resins such as a high-density polyethylene, a linear low-density polyethylene, a linear very low-density polyethylene, a linear ultralow-density polyethylene, a high-pressure-processed low density polyethylene, an ethylene-vinyl acetate copolymer, etc.; and hydrogenated products of butadiene-based polymers.

When the master batch is used in the production of the resin composition, the amount of the master batch to be added is usually less than 50 parts by weight, per 100 parts by weight of the high-density polyethylene contained in the resin composition of the present invention. This amount is preferably 20 parts ^' by weight or less, more preferably 10 parts by weight or less, from the viewpoint of the cost-effectiveness.

The resin composition of the present invention is formed into filaments such as multifilaments, monofilaments, etc., because of its superior melt-spinning performance and melt-extrudability . Preferably, this resin composition is formed into monofilaments. The filaments formed of this resin composition are superior in heat drawability and sufficient in mechanical strength. The method of producing filaments from this resin composition is superior in cost performance, since it is possible to extrude and spin the resin composition at a high discharge rate and is possible to highly draw the resulting strands by a single-step drawing operation.

As the method for forming the resin composition of the present invention into filaments, there are given the known molding methods such as a melt-spinning method, a (direct) spinning/drawing method, etc. For example, the resin composition is molten with an extruder or the like; the resulting melt is extruded from a die/nozzle via a gear pump to form a strand-like melt; the extruded strand-like melt of the resin composition is spun and is cooled with a cooling medium such as water, an air or the like; and then, if needed, the resulting strand is drawn under heating, treated by heating, coated with an oil, and is then taken up as a filament.

The sectional shape of the filament is circular, elliptic, triangular, rectangular, hexagonal or star-shaped. The fineness of the filament is usually from 50 to 500 denier, preferably from 100 to 350 denier, more preferably from 150 to 250 denier. When the filaments formed of the resin composition of the present invention are used' as monofilaments, such monofilaments are used to manufacture nets such as mosquito nets, wind screens, insect proof nets; ropes; yarns; and filters. When the filaments formed of the resin composition of the present invention are used as multifilaments, such multifilaments are used to manufacture ropes, nets, carpets, non-woven cloths, filter, shoes, clothes, etc. In particular, the filaments of the present invention are preferably used for products which are required to have insect-proofing performance, such as wind screens, insect proof nets, mosquito nets, filters, carpets, shoes and clothes .

Examples of insects as objects to be controlled by the filaments formed of the resin composition of the present invention are Arthropoda such as spiders, ticks and insects. The following are examples thereof: Ormithonyssus sylviarum, citrus red mite, Tyrophagus putrescentiae, etc. belonging to Acarina; and Atypus karshi, Pholcus phalangioides, etc. belonging to Araneae, in Arachnida: Thereuopoda clunifera, etc. belonging to Scutigeromorpha; and Bothropolys asperatus, etc. belonging to Lithobiomorpha in Chilopoda: and axidus gracilis, Nedyopus tambanus, etc. belonging to Polydesmoidea, in Chilopoda. As the insects, the following are given: Ctenolepisma villosa Escherich, etc. belonging to Thysanura; cave cricket, mole cricket, Teleogryllus emma, locusta migratoria, Schistocerca gregaria, locust, etc. belonging to Orthoptera; earwig, etc. belonging to Dermaptera; Blattella germanica, Periplaneta fuliginosa, Periplaneta Japonica, Periplaneta americana, etc. belonging to Blattaria; Japanese subterranean termite, Formosan subterranean termite, Incisitermes minor HAGEN, etc. belonging to Isoptera; Liposcelis entomophilus Enderlein, Liposcelis bostrychophilus Badonnel, etc. belonging to Psocoptera; Trichodectes canis, Felicola subrostratus, etc. belonging to Mallophaga; Pediculus humanus corporis, Pthirus pubis, Pediculus humanus, etc. belonging to Anoplura; Nilaparvata lugens Stal, Nephotettix cincticeps, Greenhous white fly, Myzus persicae, Cimex lectularius Linnaeus, Halyomorpha halys, etc. belonging to Hemiptera; dermestid beetles, Aulacophora femoralis, Sitophilus zeamais, Lyctus brunmeus, Ptinus japonicus, Popillia japonica Newman, etc. belonging to Coleoptera; cat flea, dog flea, human flea, etc. belonging to Siphonaptera; Culex pipiens pallens couguillett, Aedes aegypti, anopheles, Simuliidae, Chironomus, Psychodidae, House fly, Glossina palpalis, Tabanus trigonus, Syrphinae, etc. belonging to Diptera; Vespa, Polistes, Nesodiprion japonicus Marlatt, Dryocosmus kuriphilus, Sclerodermus nipponicus, Monomorium pharaonis, etc. belonging to Hymenoptera; and the like. Examples

Hereinafter, the present invention will be described by way of Examples thereof and Comparative Examples. In Examples and Comparative Examples, the physical properties were measured according to the following methods. (1) Melt Flow Rate (MFR, g/10 mins . in unit)

A melt flow rate was measured at 190⁰C under a load of 21.18 N according to the method regulated in JIS K7210-1995. (2) Melt Flow Rate Ratio (MFRR)

A MFRR is a quotient found by the following division: that is, a melt flow rate (MFR-H, g/10 mins. in unit) measured at 190°C under a load 211.83 N according to the method regulated in JIS K7210-1995 is divided by a melt flow rate (MFR) measured at 190°C under a load 21.18 N according to the method regulated in JIS K7210-1995.

(3) Density (kg/m³ in unit)

A density was measured according to the procedure regulated in the method A among the methods described in JIS K7112-1980. A test piece to be measured was annealed according to the method for low-density polyethylene, regulated in JIS K6760-1995.

(4) Average Pore Radius (μm in unit)

Synthetic silica was dried at 12O⁰C for 4 hours, and a pore distribution of pores with radii of from about 0.0018 to 100 μm was measured, using AutoPore III 9420 manufactured by MICROMERITICS . An average pore radius was defined as a pore radius at which the infiltration ratio of mercury became 50% of the entire infiltration amount of mercury.

(5) Specific Surface Area (m²/g in unit)

Synthetic silica to be measured was previously deaerated in vacuum at 120° for 8 hours. BELSORP-mini manufactured by BEL JAPAN, INC. was used to measure an adsorption/desorption constant temperature line, using nitrogen as an adsorbate, by the constant volume method, at an adsorption temperature of 77K, provided that the sectional area of the adsorbate was 0.162 nm². The specific area of the synthetic silica was calculated by the BET multipoint method.

(6) Oil Absorption Weight (g/100 g in unit)

An insect-controlling agent (5 cm³) was poured into a glass container, and synthetic silica heated to 5O⁰C was added little by little thereto under stirring, until any ball-like agent localized on the synthetic silica disappeared. At a point of time when any ball-like agent had disappeared, it was judged that the insect-controlling agent had been retained in the synthetic silica. The oil absorption weight of the insect-controlling agent per 100 g of the synthetic silica was calculated from the weight of the synthetic silica added and the weight of the insect- controlling agent. Example 1 1. Preparation of Insect-Controlling Agent Retainer Permethrin (Eksmin® manufactured by Sumitomo Chemical Company, Limited; density: 1.21 g/cm³) (51 parts by weight) as an insect-controlling agent was admixed with butyl hydroxytoluene (1.5 parts by weight) as an antioxidant, and the resulting mixture was dissolved under stirring. Next, SOLEX CM manufactured by Tokuyama Corp. (hereinafter referred to as Silica 1, of which the physical properties are shown in Table 1) (47.5 parts by weight) as synthetic silica was added, and the resulting mixture was stirred to obtain an insect-proofing agent retainer which contained the insect-proofing agent (hereinafter referred to as Insect-proofing agent-containing retainer A) . Next, a high-pressure-processed low-density polyethylene

(Sumikathene® G803-1 manufactured by Sumitomo Chemical

Company, Limited; MFR = 20 g/10 mins . ; density = 918 kg/m³) (60.3 parts by weight), Insect-proofing agent-containing retainer A (34.2 parts by weight) and zinc stearate (5.5 parts by weight) were kneaded in a Banbury mixer, at a set temperature of 15O⁰C and at 300 rpm, for 5 minutes. Thus, a master batch of an insect-controlling agent retainer was obtained. 2. Preparation of Resin Composition for Filaments

A high-density polyethylene (HI-ZEX® 440M, i.e., an ethylene-propylene copolymer, manufactured by PRIME POLYMER; MFR = 0.9 g/10 mins . ; density = 948 kg/m³; MFRR = 35) (100 parts by weight) and the master batch of the insect-controlling agent retainer (14.5 parts by weight) were kneaded in a Banbury mixer. Thus, a resin composition for filaments was prepared. No stickiness was felt in this resin composition. 3. Production of Filaments

An extruder of 20 mmφ with a die having 6 holes of 1.0 mmφ was used to extrude the resin composition for filaments, through the die set at 200°C and at a discharge rate of 0.9 kg/hr. The resulting strand of the resin composition was fed at a line speed of 14 m/min. and was allowed to pass through a hot water bath, and was then fed at a rate of 112 m/min. Thus, a monofilament having a fineness of 200 denier was obtained. 4. Evaluation of Bleeding Performance The filament (500 mg) was put in a glass bottle, and the bottle was capped and was then left to stand still in an oven at 60°C for 2 hours. After that, acetone (450 cm³) was added into the bottle, and the bottle was agitated for

30 minutes to thereby cleans the surface of the filament. The filament cleansed at its surface was put into a glass bottle, and the bottle was capped and was left to stand still in an oven at 60°C for one day. Then, the filament was removed from the oven, and ethanol (50 cm³) was added to the filament. Then, the filament was agitated with an agitator for 10 minutes to cleans off the insect- controlling agent bled out of the surface of the filament. The resulting cleansing liquid was measured with respect to its permethrin concentration, using a spectrophotometer for ultraviolet and visible region. The filament wiped at its surface was put in a glass bottle, and the glass bottle was capped and was again left to stand still in an oven at 60°C for 6 days. The filament was removed from the oven, and ethanol (50 cm³) was added, and the glass bottle was agitated with an agitator for 10 minutes to cleans off the insect-controlling agent bled out to the surface of the filament. The resulting cleansing liquid was measured with respect to its insect-controlling agent concentration, using a spectrophotometer for ultraviolet and visible region.

Measurement of Permethrin Concentration with Spectrophotometer for Ultraviolet and Visible Region

The surface-cleansing liquid was measured with a spectrophotometer V-650 for ultraviolet and visible region, manufactured by JASCO Corporation, under the following conditions; and the absorbances of the peaks of the permethrin within a range of 200 ± 1 nm were measured.

Measuring conditions for the spectrophotometer: cell length: 10 nm band width: 2.0 nm scanning speed: 400 nm/min. wavelength at start: 340 nm wavelength at end: 190 nm data-loading interval: 1.0 nm

In advance, a calibration curve of the absorbances of permethrin within the range of 200 ± 1 nm and the concentrations of permethrin was found by the measurement of eight different ethanol solutions of permethrin having concentrations of from 0.632 to 15.8 mg/L, using the above- described spectrophotometer.

The amount of permethrin in the surface-cleansing liquid was determined from this calibration curve. The amount of permethrin bled from the surface of the filament found one day after was defined as a quotient calculated as follows: the amount of permethrin in the cleansing liquid found one day after was divided by the measured weight of the filament. The amount of permethrin bled from the surface of the filament found 7 days after was defined as a quotient calculated as follows: the amount of permethrin in the cleansing liquid found 6 days after the one day after, i.e., 7 days after, was divided by the measured weight of the filament. The sum of the amount of permethrin bled from the surface of the filament found one day after and the amount of permethrin bled from the surface of the filament found 7 days after was defined as a cumulative amount of permethrin bled from the surface of the filament 7 days after, which was used to evaluate the amount of permethrin bled out of the surface of the filament in the initial stage of use.

The cumulative amount of permethrin bled out of the surface of the filament 7 days after was 2.23 mg/g. Example 2 Example 1 was repeated, except that Finesil CM-F manufactured by Tokuyama Corp. (hereinafter referred to as Silica 2, of which the physical properties are shown in Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition. The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 2.23 mg/g. Example 3

Example 1 was repeated, except that Finesil B manufactured by Tokuyama Corp. (hereinafter referred to as Silica 3, of which the physical properties are shown in Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition.

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 2.70 mg/g. Example 4

Example 1 was repeated, except that Finesil T-32 manufactured by Tokuyama Corp. (hereinafter referred to as

Silica 4, of which the physical properties are shown in

Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition.

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 2.53 mg/g. Example 5

Example 1 was repeated, except that Carplex FPS-5 manufactured by EVONIC INDUSTRIES (hereinafter referred to as Silica 5, of which the physical properties are shown in

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 1.73 mg/g. Example 6

Example 1 was repeated, except that Tokusil GU manufactured by Tokuyama Corp. (hereinafter referred to as

Silica 6, of which the physical properties are shown in Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition.

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 1.23 mg/g.

Comparative Example 1 Example 1 was repeated, except that Finesil X-32 manufactured by Tokuyama Corp. (hereinafter referred to as

Silica 7, of which the physical properties are shown in

Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition. The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 0.81 mg/g.

Comparative Example 2

Example 1 was repeated, except that Mizukasil P-707 manufactured by MIZUSAWA INDUSTRIAL CHEMICALS, LTD. (hereinafter referred to as Silica 8, of which the physical properties are shown in Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition. The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 0.54 mg/g. Comparative Example 3

Example 1 was repeated, except that Carplex BS-308N manufactured by EVONIK INDUSTRIES (hereinafter referred to as Silica 9, of which the physical properties are shown in

Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition. The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 0.89 mg/g. Comparative Example 4

Example 1 was repeated, except that Sipernat 880 manufactured by EVONIK INDUSTRIES (hereinafter referred to as Silica 10, of which the physical properties are shown in

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 0.70 mg/g. Comparative Example 5

Example 1 was repeated, except that Nipsil E-743 manufactured by TOSOH SILICA CORPORATION (hereinafter referred to as Silica 11, of which the physical properties are shown in Table 1) was used as the synthetic silica. No stickiness was felt in this resin composition.

The cumulative amount of permethrin bled out of the surface of this filament 7 days after was 0.40 mg/g. Example 7 1. Preparation of Insect-Controlling Agent Retainer

Permethrin (64.9 parts by weight) as the insect- controlling agent was admixed with butylhydroxytoluene (1.9 parts by weight) as the antioxidant, and the mixture was stirred and dissolved. Next, Carplex 80 manufactured by EVONIC INDUSTRIES (hereinafter referred to as silica 12, of which the physical properties are shown in Table 1) (33.2 parts by weight) as the synthetic silica was added to the resulting solution, and the mixture was stirred and mixed. Thus, an insect-controlling agent retainer which contained the insect-controlling agent (hereinafter referred to as an insect-controlling agent retainer B) was obtained.

Next, a high-pressure-processed low-density polyethylene, Sumikathene G803-1 (64.9 parts by weight), the insect-controlling agent retainer B (29.0 parts by weight) and zinc stearate (5.9 parts by weight) were kneaded at a set temperature of 150°C and at 300 rpm for 5 minutes, using a Banbury mixer. Thus, a master batch of the insect-controlling agent retainer was obtained. 2. Preparation of Resin Composition for Filaments A high-density polyethylene, HI-ZEX 440M, (100 parts by weight) and the master batch of the insect-controlling agent retainer (11.8 parts by weight) were kneaded, using a Banbury mixer, to obtain a resin composition for filaments. No stickiness was felt in this resin composition. 3. Production of Filament, and

Evaluation of Bleeding Performance

The production of filaments and the evaluation of the bleeding performance thereof were conducted in the same manners as in Example 1. The cumulative bleeding amount of the filament after 7 days had passed was 2.06 mg/g. Example 8

1. Preparation of Insect-Controlling Agent Retainer Permethrin (64.9 parts by weight) as the insect- controlling agent was admixed with butylhydroxytoluene (1.9 parts by weight) as the antioxidant, and the mixture was stirred and dissolved. Next, Carplex 8OD manufactured by EVONIC INDUSTRIES (hereinafter referred to as silica 13, of which the physical properties are shown in Table 1) (33.2 parts by weight) was added to the resulting solution, and the mixture was stirred and mixed. Thus, an insect- controlling agent retainer which contained the insect- controlling agent (hereinafter referred to as an insect- controlling agent retainer C) was obtained.

Next, a high-pressure-processed low-density polyethylene, Sumikathene G803-1 (64.9 parts by weight), the insect-controlling agent retainer C (29.0 parts by weight) and zinc stearate (5.9 parts by weight) were kneaded at a set temperature of 150°C and at 300 rpm for 5 minutes, using a Banbury mixer. Thus, a master batch of the insect-controlling agent retainer was obtained.

2. Preparation of Resin Composition for Filaments

A high-density polyethylene, HI-ZEX 440M, (100 parts by weight) and the master batch of the insect-controlling agent retainer (11.8 parts by weight) were kneaded, using a Banbury mixer, to obtain a resin composition for filaments. No stickiness was felt in this resin composition. 3. Production of Filament, and

Evaluation of Bleeding Performance

The production of filaments and the evaluation of the bleeding performance thereof were conducted in the same manners as in Example 1. The cumulative bleeding amount of the filament after 7 days had passed was 1.47 mg/g. Table 1

Claims

1. A resin composition for filaments, comprising a high- density polyethylene, an insect-controlling agent and synthetic silica, wherein the density of the high-density polyethylene is from 935 to 965 kg/m³, and the MFR thereof, from 0.1 to 6 g/10 min. ; the average pore radius of the synthetic silica is from 0.040 to 0.105 μm; and said resin composition contains 100 parts by weight of the high-density polyethylene, and 0.1 to 10 parts by weight of the insect-controlling agent and 0.1 to 10 parts by weight of the synthetic silica per 100 parts by weight of the high-density polyethylene.

2. A filament formed of the resin composition of Claim 1.