Synthetic resin mesh structure, and protective fence, fall prevention net, and animal intrusion prevention net using the same

Abstract

To provide a resin mesh structure having excellent shock absorption properties and unlikely to allow penetration or breakage by impacting bodies.SOLUTION: A synthetic resin mesh structure comprises polyester monofilament having an initial instantaneous modulus of 20 to 120 N / mm2 sec and a strength at 25% elongation of 180 N / mm2 or more arranged at least in part thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a synthetic resin mesh structure having thermoplastic resin monofilaments arranged in at least a portion thereof, and more specifically to a synthetic resin mesh structure having properties that enable it to replace metal mesh structures, and a protective fence, a fall prevention net, or an animal intrusion prevention net made using this synthetic resin mesh structure. [Background technology]

[0002] Currently, metal mesh structures are used in a variety of fields, including aquaculture cages (fisheries materials), gabions / futon cages used in bank protection construction (civil engineering materials), rockfall prevention nets (civil engineering materials, nets to prevent vehicles and animals from entering (agricultural materials, construction materials)), and automobile grill nets (vehicle materials). However, metal mesh structures have a number of problems, such as reduced durability due to oxidation and corrosion, exposure of sharp, hard metal edges when the net is broken, and poor handling due to their heavy weight. Therefore, there is a strong demand for the development of mesh structures that solve these problems.

[0003] In particular, in recent years, attempts have been made to utilize the elasticity of resins as shock absorbing materials, but conventional resin network structures have not been able to provide sufficient shock absorbing performance, and there is a strong demand for the development of network structures that solve these problems.

[0004] Among the prior art, a synthetic resin network structure has been proposed in Patent Documents 1 and 2 as one of the techniques for solving the above-mentioned problems.

[0005] Patent Document 1 aims to achieve "excellent durability even during long-term use and to be resistant to breakage due to stress concentration (page 3)," and proposes a solution to this problem: "a net with a yield strength of 15 to 35 kgf / mm 2 The document discloses "a synthetic resin network structure characterized by being constructed by arranging at least a portion of polyester monofilaments having a ratio of strength at 25% elongation / yield strength of 1.5 or less and diameter unevenness in the fiber longitudinal direction of less than 10% (Claim 1)."

[0006] Furthermore, Patent Document 2 addresses the issue of "providing a synthetic resin mesh that has high strength and excellent impact resistance against the impact of heavy objects such as falling rocks, and is effective in protecting against falling rocks

[0009] ," and as a solution to this issue, describes a mesh made of "polyester monofilament as a constituent material, with a hexagonal tortoiseshell mesh, and a tensile breaking work of 1000 kg / mm 2 The document discloses a synthetic resin mesh body for rockfall protection, which is .% or more (Claim 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5830725 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-7986 Summary of the Invention [Problem to be solved by the invention]

[0008] The above-mentioned prior art discloses a synthetic resin network structure having excellent abrasion resistance or impact resistance, but in order to widely deploy synthetic resin network structures in various fields, further improvements in both abrasion resistance and impact resistance have been desired.

[0009] According to Patent Document 1, in its examples and comparative examples, by using polyester monofilaments whose yield strength, strength at 25% elongation / yield strength ratio, diameter unevenness in the longitudinal direction of the fiber, and flattening ratio are within certain ranges, it is possible to obtain a synthetic resin network structure that has excellent durability even during long-term use and is resistant to breakage due to stress concentration. From these results, it is believed that the monofilament described in Patent Document 1 is a monofilament that can sufficiently elongate when subjected to an impact and absorb the energy of the impact.

[0010] However, although the monofilament of Patent Document 1 is capable of absorbing impact energy when used alone, when it is made into a network structure, the mesh opens widely due to its elongation, which raises concerns that the impacting object may pass through the network structure or the mesh may open widely, causing stress to concentrate in a part of the network structure and leading to breakage of the network structure starting from the part where the stress is concentrated.

[0011] According to Patent Document 2, in the examples, the tensile breaking work is 1000 kg / mm 2 It is stated that a synthetic resin mesh structure using polyester monofilament with a polyester content of 0.05% or more did not break any monofilaments in a practical evaluation test in which stones were actually dropped, and deformation of the mesh was small. From these results, it is thought that the mesh structure described in Patent Document 2 can absorb impact energy immediately after being made without stretching significantly even when it is subjected to an impact such as a falling rock.

[0012] However, the network structure of Patent Document 2 is difficult to stretch when subjected to an impact, and there is a concern that it may be easily broken when stress is concentrated in one part of the structure.

[0013] In contrast to the conventional techniques, the present invention aims to provide a resin network structure having excellent shock absorption properties. [Means for solving the problem]

[0014] After extensive consideration of the above issues, we have achieved an initial instantaneous modulus of 20 to 120 N / mm 2 sec, strength at 25% elongation is 180N / mm 2 It has been found that the above-mentioned problems can be solved by a synthetic resin network structure characterized by being constructed by disposing the above-mentioned polyester monofilament in at least a part thereof.

[0015] In the synthetic resin network structure of the present invention, The polyester monofilaments have a substantially hexagonal knotless tortoiseshell mesh structure extending in the longitudinal direction; The polyester monofilament contains 0.01 to 3.00% by mass of a silicone compound. The polyester monofilament contains 0.05 to 5.00 mass% in total of carbon black and / or titanium oxide. the thermoplastic resin contains a phosphorus compound in an amount of 0.08 to 1.00 mass% in terms of phosphorus atoms; The thermoplastic resin wire has an oxygen index of 26 or more when tested in a combustion test in accordance with the JIS L1091E method. When the polyester constituting the polyester monofilament is polyethylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.10 or less. When the polyester constituting the polyester monofilament is polybutylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.40 or less; When the polyester constituting the polyester monofilament is polytrimethylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.50 or less; However, all of these are considered to be preferable conditions. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a resin network structure that is resistant to penetration by an impacting object and tearing, and has excellent impact absorption properties. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a conceptual diagram showing the elongation-strength curve of a typical monofilament. [Figure 2] 1 is a conceptual diagram showing an example of a synthetic resin network structure of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below.

[0019] An important requirement of the network structure of the present invention is that it is constructed by disposing polyester monofilaments (hereinafter sometimes simply referred to as monofilaments) which are thermoplastic resins at least in part.

[0020] That is, when a thermosetting resin filament is used in a resin network structure, it is difficult to appropriately control the diameter and tensile properties of the filament, making it difficult to stably supply it as an industrial product. Furthermore, when a thermoplastic multifilament is used, fuzzed single filaments during the net-making process and in actual use can cause deterioration in quality and abrasion resistance. For this reason, it is necessary to configure the synthetic resin network structure of the present invention by arranging a polyester monofilament, which is a thermoplastic resin that has excellent abrasion resistance and quality, in a part of the structure.

[0021] The proportion of polyester monofilaments contained in the resin network structure of the present invention is not particularly limited, and other materials can be used not only in the connecting portions between network structures and in the joints to supports, etc., but also in the network structure main body as needed. However, in order to ensure that the network structure maintains excellent durability, it is preferable that 80% by mass or more of the network structure main body be composed of the monofilaments of the present invention, with a more preferred monofilament usage ratio of 90% by mass or more and an even more preferred range of 95% by mass or more being an example.

[0022] The monofilaments used in the synthetic resin network structure of the present invention may be used by doubling (and twisting, if necessary) a plurality of monofilaments before or during net-making. By doubling a plurality of monofilaments, it is possible to obtain a network structure that is more flexible than a network structure made of a single monofilament. There are no particular restrictions on the number of monofilaments to be doubling, but if the number of doublings is large, there is a possibility that the quality and abrasion resistance will deteriorate, as in the case where a multifilament is used in the above-mentioned network structure. Therefore, it is preferable that the diameter of the monofilaments to be doubling is 1.0 mm or more and the number of doublings is 10 or less.

[0023] As long as the scope of the present invention is satisfied, the material of the monofilament used in the thermoplastic resin network structure of the present invention can be any conventional material such as aromatic polyester, aliphatic polyester, aromatic polyamide, aliphatic polyamide, polyolefin, fluororesin, etc. However, in terms of price, versatility, ease of installation, productivity of the monofilament, and appropriate stiffness, polyester-based resins or polyamide-based resins are preferred. Among these, polyethylene terephthalate, polybutylene terephthalate, Polytrimethylene terephthalate and mixed and / or copolymer resins thereof are suitable as materials for monofilaments used in synthetic resin network structures, with polyethylene terephthalate being more preferred.

[0024] Furthermore, the monofilaments used in the synthetic resin network structure of the present invention may have an irregular cross-sectional shape or may be composite, as long as the effects of the present invention are satisfied, and may of course contain inorganic fine particles or organic compounds as needed, such as delustering agents, flame retardants, heat resistance agents, light resistance agents, UV absorbers, coloring pigments, etc., which are commonly used in synthetic fibers, or may be copolymerized with different polymers. There are no particular restrictions on the addition rate of additives or the copolymerization rate of copolymerization components as long as the effects of the present invention are not impaired, but from the viewpoint of spinnability, it is preferable that the additive content be 5% by volume or less and the copolymerization rate be 5% by mole or less.

[0025] The diameter of the monofilament used in the synthetic resin network structure of the present invention is preferably 0.5 to 5.0 mm, more preferably 1.5 to 4.0 mm, and even more preferably 2.0 to 4.0 mm. When the diameter of the monofilament satisfies the above range, it is possible to obtain a network structure that is excellent in abrasion resistance, monofilament productivity, network structure productivity, and physical properties.

[0026] The monofilament used in the synthetic resin network structure of the present invention has an initial instantaneous modulus of 20 to 120 N / mm 2The initial instantaneous modulus indicates the rate of change in strength in a very short time when an impact is applied, and is measured by the method described in the examples.

[0027] If the initial instantaneous modulus is too high, the monofilament that receives an impact will absorb the impact energy of the impacting object without stretching in a short period of time, resulting in stress concentration in some parts of the monofilament and excessive stress being applied to the connections between the network structures and to the supports, etc., causing damage to the network structure and making it difficult to protect the object to be protected.

[0028] On the other hand, if the initial instantaneous modulus is too low, the monofilament will stretch significantly upon impact even in a short period of time, causing the mesh structure itself to bend or the mesh openings to open widely, allowing the impacting object to pass through the mesh structure, making it difficult to protect the object to be protected.

[0029] That is, the initial instantaneous modulus is 20N / mm 2 If the strength is less than 120 N / mm sec, the net will stretch excessively when an impact is applied, and when used as a net to prevent rockfall or animal intrusion, these objects will slip through the net, making it difficult to protect the object. 2 If the time exceeds 1.5 seconds, the network structure cannot absorb energy by itself, and breakage of the network due to stress concentration is likely to occur.

[0030] The monofilament used in the resin network structure of the present invention has a strength of 180 N / mm at 25% elongation. 2 It is necessary that there is more than this.

[0031] The strength at 25% elongation indicates the strength of a monofilament when it is elongated by 25%. Figure 1 shows the elongation-strength curve of a typical monofilament. As shown in Figure 1, the total amount of energy absorbed when a monofilament is subjected to an external force and elongated by 25% is determined by the strength at 25% elongation.

[0032] Therefore, the amount of impact energy that the network structure can receive is represented by the strength at 25% elongation, and the strength of the resin monofilament that constitutes at least a part of the network structure that requires impact absorption is 180 N / mm at 25% elongation. 2 It is necessary that the above is true.

[0033] Furthermore, from the viewpoint of uniformly exhibiting the aforementioned impact absorption properties throughout the entire network structure, it is preferable that the monofilaments used in the synthetic resin network structure of the present invention have a diameter variation in the longitudinal direction of the fiber of less than 10%, preferably less than 5%. When the diameter variation in the longitudinal direction of the fiber satisfies the above range, stress is less likely to concentrate in the narrow diameter portions, making it possible to obtain a synthetic resin network structure that is less likely to break. On the other hand, when the diameter variation is 10% or more, stress may concentrate in the narrow diameter portions when a sudden load is applied to the synthetic resin network structure, resulting in breakage.

[0034] Furthermore, as shown in FIG. 2, the network structure of the present invention preferably has a knotless, approximately hexagonal, tortoiseshell-shaped network structure in which monofilaments extend in the longitudinal direction.

[0035] There are various methods for producing network structures, but in many network structures, if a break occurs in one place, the break continues from that point, making it difficult to maintain the shape of the entire network structure.

[0036] When producing the roughly hexagonal knotless tortoiseshell mesh of the present invention, two monofilaments aligned in the longitudinal direction are twisted together as a pair, and then the paired monofilaments are twisted together with adjacent filaments, leaving a mesh pitch interval, and then the paired monofilaments are twisted together again with the monofilaments that were originally paired, leaving a mesh pitch interval, and this process is repeated.

[0037] As a result, the aligned filaments are twisted and combined with each other, eliminating low-strength areas such as nodes, and even if a partial break occurs, the twisted structure prevents the break from spreading to other areas, making it possible to maintain a certain level of strength for the network structure.

[0038] Furthermore, the monofilaments constituting the synthetic resin network structure of the present invention preferably contain 0.01 to 3.00% by mass of a silicone compound, with a more preferred range being 0.02 to 1.00% by mass. Monofilaments containing a silicone compound in an amount within this range have good spinnability, and synthetic resin network structures using such monofilaments have the advantage of being less susceptible to breakage due to stress concentration due to good sliding properties between the monofilaments at the mesh intersections.

[0039] Examples of silicone compounds that can be used in the present invention include dimethylsiloxane (KF-96, manufactured by Shin-Etsu Silicones), polydimethylsiloxane (Bayfluid M, manufactured by Bayer), and methylphenylsiloxane (KF-54, manufactured by Shin-Etsu Silicones), and these can be obtained from the market and used.

[0040] Furthermore, the monofilament constituting the synthetic resin network structure of the present invention preferably contains a total of 0.05 to 5.00 mass% of carbon black and / or titanium oxide, with a more preferred total carbon black and / or titanium oxide content being in the range of 0.10 to 2.00 mass%. When the carbon black and / or titanium oxide content satisfies the above range, a synthetic resin network structure with excellent spinnability and weather resistance during actual use can be obtained. While the reason why the addition of carbon black and / or titanium oxide significantly improves weather resistance is unclear, it is thought that the carbon black and / or titanium oxide present in the surface layer of the monofilament absorbs and / or reflects light energy, thereby protecting the inner layer of the monofilament. Titanium oxide has two crystalline structures: anatase and rutile. Since anatase can accelerate resin degradation as a photocatalyst, rutile is more preferred. From the viewpoint that the greater the amount of the inner layer protected by carbon black and / or titanium oxide, the easier it is to maintain strength after actual use, the monofilament diameter is preferably 0.5 to 5.0 mm as described above, more preferably 1.5 to 5.0 mm, and even more preferably 2.0 to 4.0 mm, for example.

[0041] Furthermore, the monofilaments constituting the synthetic resin network structure of the present invention preferably contain 0.08 to 1.00 mass % of a phosphorus compound in terms of phosphorus atoms.

[0042] The inclusion of phosphorus compounds gives the material flame retardancy, and the oxygen index (LOI value) during combustion testing measured in accordance with the provisions of the JIS L1091E method is 26 or higher, meaning that it will not burn even when exposed to fire such as welding sparks in civil engineering and construction work sites, allowing work to be carried out safely.

[0043] Examples of phosphorus compounds include phosphorus-containing flame retardants that are commonly used as flame retardants. Preferred examples include, but are not limited to, phosphonates, phosphinates, and phosphine oxides. Among these, compounds with high heat resistance that do not decompose or scatter during melt-kneading or melt-molding are preferred. Among these compounds, phosphine oxides are preferred because they have good copolymerization reactivity with thermoplastic resins and cause little scattering during polymerization. Furthermore, the thermoplastic resin used in the present invention may be a copolymer resin obtained by copolymerizing the above phosphorus compound, or a mixture of the above copolymer resin and a conventional thermoplastic resin.

[0044] The content of the phosphorus compound in the thermoplastic resin is preferably 0.08 to 1.00 mass %, more preferably 0.40 to 0.90 mass %, of the thermoplastic resin. If the amount of phosphorus atoms exceeds 1.00 mass %, moldability will be poor, and even if a monofilament is obtained, its mechanical properties and heat resistance may be insufficient. Conversely, if the amount is less than 0.08 mass %, the flame retardant effect will be insufficient.

[0045] Furthermore, applications in which the impact resistance of the synthetic resin network structure of the present invention can be utilized include protective fences, fall prevention nets, and animal intrusion prevention nets. A protective fence is a network structure used to protect roads and houses from falling rocks, as well as to reinforce river and sea banks and slopes. By installing the synthetic resin network structure of the present invention using a fixing frame, fixing devices such as ropes and belts, and supports, etc., the speed of deformation and the amount of energy that can be absorbed are appropriately balanced even when rocks or earth and sand fall, preventing excessive stress concentration not only on the network structure itself but also on the fixing devices and supports. This allows the entire network structure to efficiently absorb impact forces and protect the protected object.

[0046] Furthermore, a fall prevention net is a mesh structure that catches building materials and construction tools that fall downward at a construction site, and the synthetic resin mesh structure of the present invention is installed on scaffolding or a building using a fixing frame, ropes, etc. When the synthetic resin mesh structure of the present invention is used as a fall prevention net, even when a heavy building material or construction tool falls, the speed of deformation and the amount of energy that can be absorbed are appropriately balanced, so that the entire protective fence structure can efficiently absorb the impact force and catch the falling object without excessive stress being concentrated not only on the mesh itself but also on the fixing frame and ropes.

[0047] Furthermore, animal intrusion prevention netting is a mesh structure for isolating human living areas from the intrusion of wild animals, and is used to separate roadsides, the boundaries between farmland and forest, and leisure facilities such as beaches from the ocean and / or forests. The synthetic resin mesh structure of the present invention is secured to posts or the like with fasteners such as belts and installed to protect human living areas. Even when an animal applies energy to this synthetic resin mesh structure through impact, the speed of deformation and the amount of energy that can be absorbed are appropriately balanced, so that excessive stress is not concentrated on the fasteners or posts, and the impact force is efficiently absorbed. As a result, the net is less likely to break or fall off the posts, and even if one break occurs, subsequent breaks do not occur, allowing animal intrusion to be prevented for a long period of time.

[0048] Next, an example of a method for producing the thermoplastic resin network structure of the present invention and the monofilaments that constitute this network structure will be described, but the production method is not limited to this.

[0049] The monofilaments constituting the thermoplastic resin network structure of the present invention can be obtained by a melt spinning method in which melt-spun undrawn monofilaments are cooled and then hot-drawn between rollers.

[0050] The viscosity of the monofilament obtained by melt spinning is preferably within the following ranges in terms of obtaining the initial instantaneous modulus and strength at 25% elongation.

[0051] In the case of polyethylene terephthalate, the intrinsic viscosity (IV) is preferably 0.60 or more and 1.20 or less, more preferably 0.65 or more and 1.10 or less.

[0052] In the case of polybutylene terephthalate, the intrinsic viscosity (IV) is preferably 0.65 or more and 1.40 or less, more preferably 0.70 or more and 1.35 or less.

[0053] In the case of polytrimethylene terephthalate, the intrinsic viscosity (IV) is preferably 0.70 or more and 1.50 or less, more preferably 0.75 or more and 1.40 or less.

[0054] If the intrinsic viscosity (IV) or relative viscosity of the monofilament is too low, the instantaneous initial modulus will be too high, and the monofilament will be able to withstand the impact energy of an impacting object without elongating in a short period of time, and the stress at 25% elongation will be small, which may result in stress being concentrated in parts of the monofilament or excessive stress being applied to the connections between the network structures and the joints to the supports, etc., causing the network structure to break and making it difficult to protect the object to be protected.

[0055] On the other hand, if the intrinsic viscosity (IV) or relative viscosity of the monofilament is too high, the instantaneous initial modulus will be too low, and the monofilament will stretch significantly even in a short period of time when subjected to an impact, causing the network structure itself to bend or the mesh to open widely, allowing the impacting object to pass through the network structure, making it difficult to protect the object to be protected.

[0056] In view of these, it is preferable to adjust the viscosity of the thermoplastic resin to be subjected to melt spinning, taking into consideration the viscosity change during the melt spinning process.

[0057] The moisture content of the thermoplastic resin to be subjected to melt spinning is preferably less than 800 ppm from the viewpoint of suppressing bubble generation during melting and suppressing hydrolysis, and is preferably 0 to 200 ppm from the viewpoint of suppressing hydrolysis, particularly when a polyester raw material is used. The moisture content can be measured by a commonly known method, for example, by coulometric titration using a Karl Fischer moisture meter (AQ-2100) manufactured by Hiranuma Sangyo Co., Ltd.

[0058] There is no particular rule regarding the method for melting the raw material resin, and it may be melted using a pressure melter, extruder, etc. The melting temperature may be changed appropriately depending on the type of raw material, but is usually set within the range of the melting point of the raw material resin +10 to 60°C from the viewpoint of melt moldability and suppression of thermal decomposition.

[0059] The molten resin is extruded through the nozzle holes after removing foreign matter through a filter in the spin pack. The shape and size of the nozzle holes can be selected appropriately based on the melt viscosity of the resin, the diameter of the monofilament, and the amount of resin extruded per hole.

[0060] A heating cylinder can be installed directly below the spinneret as needed. By passing the spun filaments through a heating cylinder maintained at 200 to 300°C, not only can the temperature of the spinneret surface be made uniform, but the orientation of the extruded filaments is also alleviated, making it possible to obtain filaments with uniform physical properties and good drawability.

[0061] The extruded filaments are then cooled and solidified in a cooling bath filled with a solvent. There are no particular restrictions on the type of solvent, but examples of cooling solvents include water and polyethylene glycol.

[0062] To obtain the monofilament that constitutes the synthetic resin network structure of the present invention, it is important to set the cooling temperature to at least 5°C below the glass transition temperature of the resin used and the cooling time to 0.5 to 2 minutes, preferably 0.9 to 1.5 minutes. A more preferable cooling temperature range is, for example, the glass transition temperature -5°C to 95°C. While the detailed mechanism is unclear, it is believed that a fiber structure in which molecular chains are not highly aligned during the elongation process is necessary to obtain a monofilament that is resistant to stress buildup during elongation, as in the present invention. Therefore, by setting the cooling temperature and cooling time within the above ranges, molecular chain mobility is ensured during the cooling process, and a molecular chain constraint region, such as a quasicrystal, is formed within the fiber structure in the cooling bath, thereby resulting in a fiber structure in which the molecular chains in the amorphous portion are not easily aligned during elongation.

[0063] On the other hand, if the cooling temperature is below the glass transition temperature minus 5°C or the cooling time is less than 0.5 minutes, the molecular chain mobility in the cooling bath is insufficient and the extruded polymer is exposed to the air for cooling, making it difficult to obtain the monofilament properties described above. Furthermore, the weight of the extruded polymer can cause uneven extrusion, resulting in a monofilament with poor flatness and diameter unevenness, which is undesirable. Furthermore, adopting production conditions in which the cooling time exceeds 2 minutes requires a larger cooling bath or a shorter residence time of the undrawn yarn in the cooling bath, which is undesirable because it reduces productivity per unit time. Regarding the upper limit of the cooling temperature, any temperature that does not cause shrinkage of the undrawn yarn due to rapid crystallization is sufficient. However, since hot water is a safe and inexpensive cooling solvent, a temperature below the boiling point of hot water, specifically 95°C or lower, is preferred.

[0064] Furthermore, in the production method of the present invention, it is important that the distance between the spinneret surface and the cooling bath liquid surface is 20 to 80 mm, preferably 20 to 60 mm. If the distance between the spinneret surface and the cooling bath liquid surface is less than 20 mm, the extruded filaments will sway significantly due to the swaying of the cooling bath liquid surface, resulting in poor spinnability. On the other hand, if the distance between the spinneret surface and the cooling bath liquid surface exceeds 80 mm, the extruded polymer, which has a high temperature and low viscosity, is easily affected by gravity, and the pulsation of the filament diameter caused by gravity will cause flattening and diameter variations. As a result, it is not possible to obtain a synthetic resin network structure, as in the present invention, that is less susceptible to network breakage due to stress concentration. If a heating barrel is used, the distance between the bottom of the heating barrel and the cooling bath liquid surface should be 20 to 80 mm.

[0065] The above-described production method exhibits particularly excellent effects when cooling unstretched monofilaments having a diameter of 3 to 10 mm, preferably 4 to 9 mm. Specifically, if the diameter of the unstretched yarn is less than 3 mm, when the monofilament is stretched to obtain a monofilament having properties suitable for use in a synthetic resin network structure, the resulting monofilament will have a small diameter, resulting in a synthetic resin network structure obtained from the monofilament with very poor physical properties. Furthermore, since the unstretched yarn is thin and the heat input from the spinning machine is small, it is likely to be rapidly cooled in the cooling bath, making it difficult to form the aforementioned structure. On the other hand, if the diameter of the unstretched yarn exceeds 10 mm, the unstretched yarn is thick and the heat input from the spinning machine is too large. This not only requires a larger stretching bath to achieve the aforementioned effects, but also tends to result in a temperature difference between the unstretched inner and outer layers during cooling, which leads to shrinkage as the surface layer solidifies, which deteriorates spinnability, and cavities form in the inner layer, significantly reducing product quality.

[0066] The cooled and solidified undrawn filament is then taken up by a take-up roll and once wound up, or once subjected to a continuous drawing step without winding up, and then subjected to a relaxation heat treatment as necessary, and then wound up by a winder.

[0067] If the surface speed of the first roll is too slow, the polymer residence time in the spinning machine will be long, adversely affecting operability, whereas if it is too fast, the total draw ratio must be small from the viewpoint of workability, resulting in a small initial instantaneous modulus and a small absorbable collision energy, so the speed of the first roll is preferably 2 to 10 m / min and the total draw ratio is preferably 3 to 5. The drawing method may be a single-stage drawing method or a multi-stage drawing method.

[0068] Furthermore, the filaments must be heated to an appropriate temperature during drawing. The heating method is not particularly limited and may be appropriately selected from heated rolls, hot dry air, steam, a heat medium bath, etc. depending on the type of resin and the diameter of the filament. However, if the resin temperature does not reach the glass transition temperature, the molecular orientation of the thermoplastic resin will not be achieved satisfactorily. If the temperature is significantly higher than the glass transition temperature, crystallization or melting will occur, and the molecular orientation of the thermoplastic resin will also not be achieved satisfactorily. Therefore, it is preferable to set the temperature to the glass transition temperature to glass transition temperature + 50°C.

[0069] Furthermore, from the viewpoint of improving processability and removing static electricity, the monofilament may be provided with 0.1 to 1.5% by mass of oil during production. If the amount of oil applied is less than 0.1% by mass, the effect of applying the oil is unlikely to be achieved, whereas if the amount of oil applied exceeds 1.5% by mass, the guides in the next process may become dirty, potentially worsening processability.

[0070] Thus, the monofilament to be used in the synthetic resin network structure of the present invention can be obtained.

[0071] Next, a method for producing a network structure using the monofilament will be described. From the viewpoint of breakage resistance, the network structure made of synthetic resin of the present invention is preferably a knotless network having a substantially hexagonal tortoiseshell mesh structure.

[0072] The mesh size of the synthetic resin network structure of the present invention is not particularly limited and can be changed as appropriate depending on the intended use, but from the viewpoints of product weight, preventing leakage of contents, and protecting the object from falling rocks, invading animals, etc., it is preferable that the mesh size be 20 to 80 mm.

[0073] The method for producing the synthetic resin network structure of the present invention is not limited, and a method can be used in which a wire mesh-making device is used to make a mesh using an oven, hot roll, or hot air blower attached to the raw material supply section or mesh-making section, which preheats the monofilaments to a temperature in the range from the glass transition temperature to the melting point of the monofilaments, and then the structure is fixed using cold air at a temperature below the glass transition temperature. [Example]

[0074] The following examples further illustrate aspects of the present invention. The definitions and measurement methods of the properties used in the specification and examples are as follows. The number of measurements in each evaluation is 1 unless otherwise specified.

[0075] [diameter] Using a coolant-proof micrometer (measurement range 0 to 25 mm) manufactured by Mitutoyo Corporation, the major and minor diameters were measured at the same point for five samples while rotating the monofilament, and the overall average was taken as the diameter (hereinafter referred to as R).

[0076] [Initial instantaneous modulus] Measurements were carried out using a Tensilon UTM-4-100 tensile testing machine manufactured by Orientec Co., Ltd., in accordance with JIS L10138.5.1, with a constant tension grip distance of 250 mm and a pulling speed of 300 mm / min. From the obtained data, the change in stress 0.5 seconds after the start of pulling was calculated using the following formula, where A is the change in stress and S is the cross-sectional area of the monofilament.

[0077] The cross-sectional area of the monofilament is S = (R / 2) × (R / 2) × 3.14 Initial instantaneous modulus = 2 x A / S [Strength at 25% elongation] Measurements were carried out using a Tensilon UTM-4-100 tensile testing machine manufactured by Orientec Co., Ltd., in accordance with JIS L10138.5.1, with a constant tension grip distance of 250 mm and a pulling speed of 300 mm / min. From the obtained data, the strength at 25% elongation was calculated using the following formula, where B is the strength and S is the cross-sectional area of the monofilament.

[0078] Strength at 25% elongation=B / S [Intrinsic viscosity (IV)] The relative viscosity η of a solution in which 8 g of sample was dissolved in 100 ml of orthochlorophenol was measured at 25°C using an Ostwald viscometer, and the intrinsic viscosity (IV) was calculated using the approximate formula: 0.0242η + 0.2634.

[0079] [Drop test] The metal frame of the mesh structure, stretched over an iron frame with sides of 2 m, was fixed horizontally to the ground, and a 100 kg conical weight was dropped from a height of 1 m onto the mesh structure. The number of broken threads after the drop and the mesh opening ratio of the mesh where the conical weight penetrated were measured. The diagonal length of the mesh was measured before and after the test, and the mesh opening ratio was calculated using the following formula. Each measurement value was calculated twice for each sample, and the average value was used.

[0080] Opening rate (%) = ([Diagonal length after test] - [Diagonal length before test]) ÷ [Diagonal length before test] × 100 [Determination of network structure] From the number of broken threads and the mesh opening rate obtained from the above test, if the number of broken threads is 3 or more or the mesh opening rate is 20% or more, it is considered unsuitable (×). A sample with 1 or 2 broken threads and an opening rate of less than 20% was judged as acceptable (◯), while a sample with 0 broken threads and an opening rate of less than 10% was judged as good (◎).

[0081] [Raw materials] Using a rotary vacuum dryer, polyethylene terephthalate chips manufactured by Toray Industries, Inc. (titanium oxide content 0.1% by mass, intrinsic viscosity (IV) 0.66, glass transition temperature 69°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material A.

[0082] Using a rotary vacuum dryer, polyethylene terephthalate chips manufactured by Toray Industries, Inc. (titanium oxide content 0.1% by mass, intrinsic viscosity (IV) 0.70, glass transition temperature 69°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material B.

[0083] Using a rotary vacuum dryer, polyethylene terephthalate chips manufactured by Toray Industries, Inc. (titanium oxide content 0.1% by mass, intrinsic viscosity (IV) 1.15, glass transition temperature 69°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material C.

[0084] Chips obtained by adding 20% by mass of carbon black to raw material A using a twin-screw extruder at a processing temperature of 285°C were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and these chips were used as raw material D.

[0085] Chips obtained by adding 10% by mass of dimethylpolysiloxane (Silicone Oil KF96 manufactured by Shin-Etsu Chemical Co., Ltd.) to raw material A using a twin-screw extruder with a processing temperature of 275°C were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and these chips were used as raw material E.

[0086] Using a rotary vacuum dryer, polyethylene terephthalate chips copolymerized with a phosphorus compound (manufactured by Toray Industries, Inc., phosphorus atom content 1.1 mass%, intrinsic viscosity (IV) 0.75) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material F.

[0087] Using a rotary vacuum dryer, polyolefin terephthalate chips manufactured by Toray Industries, Inc. (intrinsic viscosity (IV) 0.80, glass transition temperature 45°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material G.

[0088] Using a rotary vacuum dryer, polyolefin terephthalate chips manufactured by Toray Industries, Inc. (intrinsic viscosity (IV) 1.20, glass transition temperature 45°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material H.

[0089] Using a rotary vacuum dryer, polytrimethylene terephthalate chips manufactured by Toray Industries, Inc. (intrinsic viscosity (IV) 1.40, glass transition temperature 48°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material I.

[0090] Using a rotary vacuum dryer, polyethylene terephthalate chips manufactured by Toray Industries, Inc. (titanium oxide content 0.1% by mass, intrinsic viscosity (IV) 1.21, glass transition temperature 69°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material J.

[0091] Using a rotary vacuum dryer, polyethylene terephthalate chips manufactured by Toray Industries, Inc. (titanium oxide content 0.1% by mass, intrinsic viscosity (IV) 0.62, glass transition temperature 69°C) were dried at a drying temperature of 110°C until the moisture content reached 60±20 ppm, and the resulting chips were used as raw material K.

[0092] [Examples 1 to 17] The mixed raw materials, which were blended with raw materials A, B, C, D, E, F, G, H, and I at the blend ratios shown in Table 1, were fed into a melt spinning apparatus equipped with a φ60 mm (L / D = 25) single-screw extruder and melted at a spinning temperature of 285°C. The molten resin was metered using a gear pump so that the diameter after drawing was as shown in Table 1. The molten resin was then filtered through a #200 metal fabric filter in the spinning pack and spun through a nozzle hole with a pore diameter of 15 mm and a hole length of 10 mm. The spun strand was introduced into a cooling bath filled with warm water at 70°C and cooled for at least 30 seconds before being taken up by the first roll. The taken-up undrawn monofilament was continuously drawn between the first and second rolls at the draw ratio shown in Table 1 without being wound up once, and then relaxed to 1x between the second and third rolls before being wound up on a winder. Between the first and second rolls, a 1500 mm long hot water bath was installed as a heat source for stretching, and heating was performed at the temperature shown in Table 1. Between the second and third rolls, a 2000 mm long dry heat oven with an internal temperature of 160°C was installed. The obtained monofilament was then formed into a knotless net having a hexagonal tortoiseshell mesh structure by the method described in the examples of Patent Document 1. The properties of the monofilament thus obtained and the synthetic resin network structure are shown in Table 1.

[0093] [Table 1-1]

[0094] [Table 1-2]

[0095] As is clear from Table 1, the monofilaments used in the synthetic resin network structure of the present invention and the method for producing the monofilaments have excellent spinnability, and furthermore, the synthetic resin network structure using the multifilaments has excellent physical properties even after actual use.

[0096] [Comparative Example 1] A mixed raw material, prepared by blending raw materials J, K, C, and D at the blend ratios shown in Table 2, was fed into a melt spinning apparatus equipped with a φ60 mm (L / D = 25) single-screw extruder and melted at a spinning temperature of 285°C. The molten resin was metered using a gear pump to obtain the diameter after drawing shown in Table 2, then filtered through a #200 metal fabric filter in the spinning pack and spun from a nozzle hole with a pore diameter of 15 mm and a hole length of 10 mm. The spun strand was introduced into a cooling bath filled with hot water at the temperature shown in Table 2, allowed to pass through the bath for the cooling time shown in Table 2, and then taken up by the first roll rotating at a surface speed of 5.21 m / min. The taken-up undrawn monofilament was continuously drawn between the first and second rolls at the draw ratio shown in Table 2 without being wound up once, then relaxed to 1x between the second and third rolls, and then wound up on a winder. Between the first and second rolls, a 1500 mm long hot water bath was installed as a heat source for stretching, and heating was performed at the temperature shown in Table 2. Between the second and third rolls, a 2000 mm long dry heat oven with an internal temperature of 160°C was installed. The obtained monofilament was then formed into a knotless net having a hexagonal tortoiseshell mesh structure by the method described in the examples of Patent Document 1. The properties of the monofilament thus obtained and the synthetic resin network structure are shown in Table 2.

[0097] [Comparative Examples 2, 3, and 4] The same procedures as in Comparative Example 1 were carried out except that the conditions were changed as shown in Table 2 by changing the discharge rate and the immersion length of the undrawn yarn in the cooling bath. The properties of the obtained monofilament and synthetic resin network structure are shown in Table 2.

[0098] [Table 2]

[0099] As is clear from Table 2, if the range of the present invention is exceeded, it is difficult to obtain monofilaments that can be used in the synthetic resin network structure of the present invention, and synthetic resin network structures using monofilaments outside the range of the present invention were inferior in durability after actual use.

[0100] That is, as described in Comparative Examples 1 and 2, when the initial instantaneous modulus was less than 20, the mesh opening ratio of the network structure after the drop test became too large, and as a result, the synthetic resin network structure obtained also had poor durability after actual use.

[0101] As described in Comparative Example 3, when the initial instantaneous modulus exceeded 120, the number of breakages of the monofilaments constituting the network structure increased in the drop test, and the resulting synthetic resin network structure also had poor durability after actual use.

[0102] As described in Comparative Example 4, even when the stress at 25% elongation was less than 180 N / mm, the number of breakages of the monofilaments constituting the network structure increased in the drop test, and the resulting synthetic resin network structure also had poor durability after actual use. [Industrial Applicability]

[0103] The synthetic resin mesh structure of the present invention is lighter than conventional metal mesh structures and therefore easier to handle, and is less likely to break due to stress concentration. Therefore, it can be applied to a variety of fields, such as aquaculture cages (fisheries materials), gabions / futon baskets / revetment nets used in bank protection construction methods (civil engineering materials), rockfall prevention nets (civil engineering materials), nets to prevent vehicles and animals from entering (agricultural materials, construction materials), and automobile grill nets (vehicle materials).

Claims

1. Initial instantaneous modulus is 20 to 120 N / mm ２ ・sec, strength at 25% elongation is 180N / mm ２ A synthetic resin network structure characterized in that the above polyester monofilament is disposed at least in part.

2. 2. The synthetic resin network structure according to claim 1, wherein the polyester monofilaments have a knotless, approximately hexagonal, tortoiseshell-shaped network structure extending in the longitudinal direction.

3. 2. The synthetic resin network structure according to claim 1, wherein the polyester monofilament contains 0.01 to 3.00% by mass of a silicone compound.

4. 2. The synthetic resin network structure according to claim 1, wherein the polyester monofilament contains 0.05 to 5.00 mass % in total of carbon black and / or titanium oxide.

5. 2. The synthetic resin network structure according to claim 1, wherein the polyester monofilament has an oxygen index of 26 or more in a combustion test measured in accordance with the provisions of JIS L1091E method.

6. 2. The synthetic resin network structure according to claim 1, wherein the polyester monofilament contains a phosphorus compound in an amount of 0.08 to 1.00 mass % calculated as phosphorus atoms.

7. When the polyester is polyethylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.10 or less; When the polyester is polybutylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.40 or less; When the polyester is polytrimethylene terephthalate, the intrinsic viscosity (IV) of the monofilament is 1.50 or less.

2. The synthetic resin network structure according to claim 1, wherein:

8. A protective fence comprising the synthetic resin mesh structure according to any one of claims 1 to 7.

9. A fall prevention net comprising the synthetic resin network structure according to any one of claims 1 to 7.

10. An animal intrusion prevention net comprising the synthetic resin mesh structure according to any one of claims 1 to 7.

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