JP7748700B2 - Continuous wire rod - Google Patents

Description

The present invention relates to a continuous wire made of polyester resin, particularly to a continuous wire used for various materials such as woven fabrics, knitted fabrics, nets, and ropes.

Traditionally, polyester resins have been used in a wide range of applications, including molded products, films, fibers, and nonwoven fabrics, due to their excellent mechanical properties, heat resistance, chemical resistance, and dimensional stability, as well as their cost-effectiveness and recyclability. Continuous wire made from polyester resins is also used in a variety of applications, including papermaking, sewage filters, rubber reinforcement, fire hoses, hook-and-loop fasteners, fishing nets, ball-stop fences, industrial brushes, fishing line, and racket strings. Resin wire other than polyester is made from polyamide, which offers superior abrasion resistance and soil releasability (soil release) compared to polyester, making it suitable for certain applications. However, polyamide wire has issues with dimensional stability and heat resistance, and there is a demand for it to be replaced by polyester wire with improved abrasion resistance and stain resistance.

Technologies for improving the abrasion resistance of polyester wire include wire made from a polyester resin composition in which calcium carbonate with a specific particle distribution is added to polyester (Patent Document 1), and wire made from a polyester resin composition in which modified polyethylene is added to polyester (Patent Document 2). However, the technology disclosed in Patent Document 1 reduces the mechanical properties of the polyester wire due to the inclusion of inorganic particles such as calcium carbonate, and the technology disclosed in Patent Document 2 reduces heat resistance due to the addition of modified polyethylene, making it difficult to apply to industrial material applications.

On the other hand, technologies for improving the stain resistance of polyester wire include wire made from a polyester resin composition in which silicone oil is added to polyester (Patent Document 3), and wire made from a polyester resin composition in which a fluororesin is added to polyester (Patent Document 4).

JP 2012-107348 A Japanese Patent Application Publication No. 06-57528 JP 2010-242254 A Japanese Patent Application Publication No. 09-49121

As mentioned above, studies have been conducted to improve the abrasion resistance and stain resistance of polyester wires separately, but no wires have been developed that combine both abrasion resistance and stain resistance. The objective of the present invention is to provide a continuous wire made from a polyester resin that combines the mechanical properties, durability, and heat resistance required for practical use, while also providing both abrasion resistance and stain resistance.

The present invention solves the above-mentioned problems and provides a polyester-based continuous wire having a wire diameter of 0.1 mm or more, wherein at least a surface layer of the wire is made of a polyester resin composition,
The polyester resin composition contains 0.5 to 10 parts by mass of an ester-based thermoplastic elastomer and 0.5 to 10 parts by mass of a polyetheramide-based polymer, per 100 parts by mass of polyester .

According to the present invention, at least the surface of the continuous wire is composed of a polyester-based resin composition containing an ester-based thermoplastic elastomer and a polyetheramide-based polymer, and therefore the continuous wire has practical mechanical properties, durability, and heat resistance, as well as both abrasion resistance and stain resistance, making it possible to provide a polyester-based continuous wire that is suitable for use in a variety of materials.

The polyester-based continuous wire of the present invention is a wire that is continuous in the longitudinal axial direction and is composed of a polyester-based resin. The external cross-sectional shape of the continuous wire is not particularly limited and may be circular, elliptical, polygonal, or other shapes, and may be selected appropriately depending on the application, but a circular cross section is preferred in terms of mechanical properties and versatility.

The wire diameter of the continuous wire is 0.1 mm or more. If it is less than 0.1 mm, it will not be able to withstand the tension and abrasion that occurs during the manufacturing process for materials such as woven and knitted fabrics, or during practical use after manufacturing. There is no particular upper limit to the wire diameter, but it should be around 3 mm.

At least the surface layer of the continuous wire of the present invention is composed of a specific polyester resin composition. By coating the surface of the continuous wire with this specific polyester resin composition, it combines both abrasion resistance and stain resistance. The continuous wire may be in a single-phase form composed solely of this specific polyester resin composition, or it may be a composite continuous wire in which the surface layer of the continuous wire is composed of the polyester resin composition and the remaining portions are composed of other polyester-based resins. A composite continuous wire preferably has a two-layer structure consisting of a core and a coating surrounding the core. In a two-layer structure consisting of a core and a coating, the number of cores is preferably one, but multiple cores may also be present. When there are multiple cores, each of the cores is present in the coating, forming a so-called sea-island structure in which the cores form islands and the coating forms a sea. When there are multiple cores, the number of cores is preferably approximately 2 to 20. The composite ratio (area ratio) between the core and the coating is preferably 100:5-200, and can be selected appropriately taking into consideration the mechanical properties required depending on the wire diameter and application. However, in order to achieve both improved physical properties derived from the core and the abrasion resistance and stain resistance derived from the coating, a core:stain ratio of 100:10-100 is more preferable. In the case of a two-layer structure consisting of a core and a coating, a combination in which the core is made of polyethylene terephthalate and the sheath is made of a specific polyester resin composition is preferred from the standpoints of mechanical properties, durability, heat resistance, abrasion resistance, and stain resistance.

The polyester resin composition of the present invention contains 0.5 to 10 parts by mass of an ester-based thermoplastic elastomer and 0.5 to 10 parts by mass of a polyetheramide-based polymer relative to 100 parts by mass of polyester , and this polyester resin composition constitutes at least a surface layer of the continuous wire and covers the surface of the continuous wire.

The polyester used in the present invention is not particularly limited as long as it has an ester bond in the molecule. Examples of aromatic polyesters include polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate, and examples of aliphatic polyesters include polylactic acid, polybutylene succinate, and polycaprolactone. Of these, polyethylene terephthalate is preferred from the standpoints of heat resistance, mechanical properties, and economy.

The above-mentioned polyesters may be copolymerized with other dicarboxylic acid components, diol components, or oxycarboxylic acid components, as long as the effects of the present invention are not impaired. Alternatively, a blend of at least two of the above-mentioned polyesters may be used. Examples of other copolymerizable components include dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, phthalic anhydride, sebacic acid, adipic acid, azelaic acid, succinic acid, and ε-caprolactone, and diol components such as ethanediol, diethylene glycol, propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, cyclohexane glycol, and cyclohexanedimethanol.

The polyester used in the present invention may be virgin or recycled, or may be a combination of virgin and recycled polyester in an appropriate ratio.

The relative viscosity of the polyester should be 1.4 or higher, and more preferably 1.5 or higher, to improve the mechanical properties of the wire and achieve excellent dimensional stability. The relative viscosity of the polyester was measured at 20°C using an Ubbelohde viscometer and a 0.5% phenol/tetrachloroethane equal-mass mixed solution as the solvent.

The thermoplastic elastomer used in the present invention is an ester-based thermoplastic elastomer, from the viewpoints of compatibility with the polyester base and heat resistance. Furthermore, for purposes such as improving compatibility with polyester, a thermoplastic elastomer having a maleic anhydride group, an acrylic acid group, an acrylic acid ester, a fumaric acid ester, an epoxy group, a glycidyl group, or the like copolymerized in the main chain or graft-polymerized in the side chain may be used. In the present invention, the thermoplastic elastomer preferably has a durometer hardness measured according to JIS K 6253 of either a Type D durometer hardness of 50 or less or a Type A durometer hardness of 95 or less. A Type D durometer hardness exceeding 50 or a Type A durometer hardness exceeding 95 tends to result in poor improvement in abrasion resistance in the resulting continuous wire. Furthermore, the melt index of the thermoplastic elastomer (JIS K7210, measured at 230°C and under a load of 2.16 kg) is preferably 15 g/10 min or more, more preferably 20 g/10 min or more. If the melt index of the thermoplastic elastomer is less than 15 g/10 min, the dispersibility of the thermoplastic elastomer in the polyester matrix in the resulting continuous wire tends to be poor, making it difficult to obtain an improvement in abrasion resistance. From the viewpoint of spinning stability when producing the continuous wire, the upper limit of the melt index is preferably 100 g/10 min, and more preferably 60 g/10 min or less.

In the polyester resin composition, the ester-based thermoplastic elastomer is contained in an amount of 0.5 to 10 parts by mass, preferably 2 to 6 parts by mass, per 100 parts by mass of polyester. If the content of the ester-based thermoplastic elastomer is less than 0.5 parts by mass, the abrasion resistance of the continuous wire will not improve, and if it exceeds 10 parts by mass, the mechanical strength and dimensional stability of the continuous wire will tend to decrease, making it impossible to achieve the object of the present invention.

The resin composition of the present invention contains a polyetheramide-based polymer (such as polyetheresteramide, polyetheramide, or polyetheramideimide), and from the viewpoints of heat resistance and ease of handling, the polyetheramide-based polymer (such as polyetheresteramide, polyetheramide, or polyetheramideimide) is used . In the polyester resin composition, the polyetheramide-based polymer is contained in an amount of 0.5 to 10 parts by mass, preferably 2 to 5 parts by mass, per 100 parts by mass of polyester. If the content of the polyetheramide-based polymer is less than 0.5 parts by mass, the stain resistance of the continuous wire cannot be improved, and if it exceeds 10 parts by mass, the continuous wire will not have sufficient strength for practical use, and the productivity and handleability of the continuous wire will tend to be poor.

The polyester used in the present invention may contain a small amount of other thermoplastic resins, as long as the object of the present invention is achieved. Examples include polyamides, polyolefins, acrylic resins, vinyl acetate resins, vinyl chloride resins, vinylidene chloride resins, polytetrafluoroethylene, and silicone resins, and these may be added alone or in combination.
The polyester used in the present invention may also contain various additives as desired. For example, dyes, pigments, dispersants, compatibilizers, spreaders, plasticizers, viscosity modifiers, flame retardants, lubricants, UV absorbers, infrared absorbing materials, microwave absorbing materials, light stabilizers, antioxidants, pH adjusters, antibacterial agents, preservatives, fillers, heat resistance agents, antistatic agents, conductive materials, thermally conductive materials, and crystal nucleating agents may be added. In particular, additives such as UV absorbers, light stabilizers, antioxidants, and heat resistance agents may be added to improve the performance of not only the polyester but also the thermoplastic elastomer and hydrophilic component. However, in consideration of maintaining the practical strength of the continuous wire, the total amount of additives (thermoplastic elastomer, hydrophilic component, and additives) blended into the polyester resin composition constituting the surface of the continuous wire is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, per 100 parts by mass of the polyester.

For the continuous wire of the present invention to have heat resistance when applied to various material applications, it is desirable for the tensile strength to be 4N or more after dry heat treatment at 180°C for 30 minutes. If it is less than 4N, it will not be able to withstand the loads during processing or practical use. A more preferable tensile strength is 30N or more, and even more preferably 60N or more. Note that while a higher tensile strength is better, an upper limit of approximately 1000N is considered sufficient. Note that a larger wire diameter will increase the strength (N) of the wire even if the strength per unit cross-sectional area (MPa) is low, but the strength per unit cross-sectional area (tensile strength after dry heat treatment at 180°C for 30 minutes) should be 300MPa or more, preferably 400MPa or more. In this invention, the tensile test after dry heat treatment at 180°C for 30 minutes involves placing a sample wrapped around a metal frame in a hot air dryer heated to 180°C, heat treating it for 30 minutes, removing it, and storing it under standard conditions (temperature 20±2°C, relative humidity 65±4%) for at least 24 hours before applying a load to it using a tensile tester until it broke. The tensile test was performed under conditions of a grip distance of 250 mm, a pulling speed of 300 mm/min, and n=5. The average values of the maximum strength and elongation at break were calculated, and these average values were used as the tensile strength and breaking elongation.

The tensile elongation of the continuous wire of the present invention is preferably 10 to 45%, and more preferably 12 to 40%. If it is less than 10%, the wire will be more brittle and less durable against flexural fatigue. On the other hand, if it exceeds 45%, the rigidity of the wire as a material will decrease, and when used in filters, for example, the filtration accuracy may be insufficient.

An example of the method for producing the continuous wire of the present invention is described below. A pre-dried polyester resin composition (basically in pellet form) is prepared, and melt-spun from a spinneret using an extruder-type spinning device at a spinning temperature of approximately 265-300°C. The spun material is then cooled in a warm water bath of approximately 40-80°C to obtain an unstretched wire. This unstretched wire undergoes a first-stage stretching (stretch ratio of approximately 2.5-4.5 times) in a water bath of approximately 70-95°C, followed by a second-stage stretching (stretch ratio of approximately 1.1-2.5 times) in a hot air atmosphere of approximately 100-300°C. A subsequent relaxation heat treatment of approximately 0-20% in a hot air atmosphere of approximately 100-300°C yields the continuous wire of the present invention. In the case of wire with a two-layer structure, dried resins or resin compositions (both basically in pellet form) for the core and sheath are prepared separately, and the process is the same as above, except that they are melt-spun from a core-sheath composite spinneret using an extruder-type spinning device at a spinning temperature of approximately 265-300°C.

To prepare the polyester resin composition, the ester-based thermoplastic elastomer, polyetheramide-based polymer , and other additives can be individually prepared and dry-blended with polyester pellets, which can then be introduced into a melt spinning apparatus to produce wire. Alternatively, compound pellets or masterbatches, in which the raw materials are pre-melted and kneaded in a predetermined ratio, can be used. To adjust handleability and surface properties, a fiber oil or other additives can be applied online before or after stretching, or a coating or dipping process can be used to impart a coating film. Furthermore, post-processing such as plasma treatment can be performed to adjust water affinity and processability.

FIG. 1 shows a schematic perspective view of a bending wear test for evaluating wear resistance.

The present invention will be specifically described below using examples, in which various values were measured as follows.
(1) Wire diameter The continuous wire was measured at 20 points at intervals of 50 cm, and the average value was taken as the wire diameter (mm).
(2) Tensile test: Since continuous wire rods are usually wound up, a required amount was unwound and left at room temperature for 24 hours or more, and then a load was applied to the wire using a tensile tester until it broke, and the maximum strength and breaking elongation were measured. The conditions for the tensile test were a grip distance of 250 mm, a pulling speed of 300 mm/min, and the average values measured with n=5 were taken as the maximum strength (N) and breaking elongation (%).
(3) Tensile test (after heat treatment)
The required amount of continuous wire was unwound and tightly wound around a metal frame, and then placed in a hot air dryer heated to 180°C. After 30 minutes, it was removed and left to stand for 24 hours or more under standard conditions (temperature 20±2°C, relative humidity 65±4%). After that, it was measured with a tensile tester, and a load was applied until it broke, and the maximum strength and breaking elongation were measured. The tensile test conditions were a grip distance of 250 mm, a pulling speed of 300 mm/min, and n=5. The average values measured were used as the maximum strength (N) and breaking elongation (%).
(4) Abrasion resistance (flexural abrasion test)
A stainless steel hexagonal rod with a 12 mm opposite side was used as the abrasion body. As shown in Figure 1, a sample (wire rod) was brought into contact with this abrasion body at an angle of approximately 90 degrees, and a predetermined load was applied to one end of the sample, causing it to rub back and forth at a stroke width of 300 mm and a stroke speed of 30 times/min, and the number of times the sample was rubbed back and forth until it broke was measured. Five measurements were taken for each sample, and the average of the obtained numbers was taken as the abrasion count for abrasion resistance. The predetermined load was 3.2 kg per cross-sectional area ( ^mm2 ) of the sample. That is, for example, if the wire diameter is 0.4 mm, a load of 400 g was used.
(5) Pull-out test (stain resistance)
A 4 mm diameter circular hole was drilled in a resin board (5 mm thick), a continuous wire rod of sufficient length (approximately 20 cm) was passed through the center of the hole so that at least 15 cm of the continuous wire rod protruded from the upper surface of the resin board, and wood putty (manufactured by Cemedine Co., Ltd., product name "Wood Putty A Ash White") was filled in, and the board was left to dry at room temperature. If the volume of the wood putty decreased due to drying while it was left to dry, additional wood putty was filled in so that the upper and lower surfaces of the filled wood putty and the upper and lower surfaces of the resin board were approximately the same. After the final additional filling, the resin plate was left for at least two days to allow the wood putty to dry thoroughly. The wire rod protruding from the underside of the resin plate and excess wood putty were then cut off with a cutter along the underside of the resin plate. The resin plate with the wire rod secured by the wood putty was then horizontally fixed to the bottom of a tensile tester. Meanwhile, the wire rod protruding at least 15 cm from the top surface of the resin plate was vertically lifted and secured with a capstan chuck. When secured with the capstan chuck, the wire rod (sample) was measured at a chuck distance of 100 mm (the distance from the top surface of the resin plate to the capstan chuck), a tensile speed of 100 mm/min, and n = 5. The maximum strength of the tensile test was measured, and the average value was taken as the pull-out strength (N). The smaller the pull-out strength value, the easier it was to remove firmly adhered dirt (wood putty), and the soil release properties were evaluated.
(6) Melt Index The melt index of a thermoplastic elastomer was determined in accordance with JIS K7210 using a melt indexer at a measurement temperature of 230°C and a load of 2.16 kg, with n=5, and the average value was obtained.
(7) Durometer Hardness The durometer hardness of the thermoplastic elastomer was measured at a temperature of 20°C using a durometer on a plate-shaped test piece having a thickness of 6 mm prepared by hot press molding in accordance with JIS K6253.
(8) Relative Viscosity The relative viscosity of the polyester chips was measured at 20° C. using an Ubbelohde viscometer with a 0.5% phenol/tetrachloroethane mixed solution in equal mass as a solvent.

Example 1
A chip blend of 100 parts by weight of polyethylene terephthalate chips (relative viscosity 1.5), 4 parts by weight of a thermoplastic elastomer (ester-based, melt index 30 g/10 min, durometer hardness D30), and 2 parts by weight of a polyether ester amide block copolymer was melt-spun at 280°C using a conventional extruder-type melt spinning apparatus. The spun continuous wire was cooled in a warm water bath at 50°C to obtain an unstretched wire. Without winding, this unstretched wire was subjected to a first-stage stretching at a draw ratio of 3.8 times in a 90°C warm water bath, followed by a second-stage stretching (draw ratio of 1.4 times) while passing through a heating zone at 200°C so that the total draw ratio was 5.4 times. It was then passed through a heating zone at 200°C for a 4% relaxation heat treatment, yielding a continuous wire. The wire diameter of the resulting continuous wire was 0.4 mm.

Example 2
A continuous wire was obtained in the same manner as in Example 1, except that the blending amount of the thermoplastic elastomer was 8 parts by mass and the blending amount of the hydrophilic component was 5 parts by mass. The wire diameter of the obtained continuous wire was 0.4 mm.

Example 3
To obtain a continuous wire having a composite cross section in which a core is surrounded by a coating, a chip blend of 100 parts by mass of polyethylene terephthalate chips (relative viscosity 1.5) was prepared as the resin for the core, and 4 parts by mass of a thermoplastic elastomer (ester-based, melt index 30 g/10 min, durometer hardness D30) and 2 parts by mass of a polyether ester amide block copolymer was prepared. The resulting mixture was then melt-spun at 280°C using a conventional extruder-type melt conjugate spinning apparatus. The core and coating were weighed so that the volume ratio of the core to the coating was 7/3. The spun continuous wire was cooled in a 50°C warm water bath to obtain an undrawn wire. This undrawn wire was, without being wound up, subjected to a first-stage drawing at a draw ratio of 3.8 in a hot water bath at 90°C, then to a second-stage drawing (draw ratio of 1.4) while passing through a heating zone at 200°C so that the total draw ratio became 5.4, and then to a 4% relaxation heat treatment by passing through a heating zone at 200°C, thereby obtaining a continuous wire with a two-layer structure. The wire diameter of the obtained continuous wire was 0.4 mm, and the area ratio of the core/coating in the cross section was 7/3.

Comparative Example 1
A single-layer continuous wire made of only polyethylene terephthalate was obtained in the same manner as in Example 1, except that only polyethylene terephthalate chips were used. The wire diameter of the obtained continuous wire was 0.4 mm.

Comparative Example 2
A single-layer continuous wire was obtained in the same manner as in Example 1, except that a polyester resin composition prepared by chip-blending 100 parts by mass of polyethylene terephthalate chips with 4 parts by mass of thermoplastic elastomer was used. The diameter of the obtained continuous wire was 0.4 mm.

Comparative Example 3
A single-layer continuous wire was obtained in the same manner as in Example 1, except that a chip blend of 2 parts by mass of a hydrophilic component was used per 100 parts by mass of polyethylene terephthalate chips. The diameter of the obtained continuous wire was 0.4 mm.

The physical properties of the obtained continuous wire rods of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

The continuous wires of Examples 1 to 3 had practically sufficient tensile strength and tensile strength comparable to the continuous wire of Comparative Example 1, which consisted only of polyester, and also had better abrasion resistance than Comparative Example 1. Furthermore, the pull-out strength of Examples 1 to 3 was significantly lower than that of Comparative Example 1, demonstrating excellent soil release properties. This is thought to be due to the improved hydrophilicity of the wire surface of the continuous wires of the Examples, allowing wood putty that had been adhered as dirt to easily come off.

In Comparative Example 2, improved abrasion resistance was observed, but the pull-out strength was about the same as in Comparative Example 1, and soil release properties were insufficient. In Comparative Example 3, improved soil release properties were observed, but abrasion resistance was poor.

As is clear from Table 1, the continuous wires of Examples 1 to 3 of the present invention have the mechanical properties and heat resistance required for practical use, and because the wire surface has been modified, they also have excellent wear resistance and soil release properties.

Claims (3)

A polyester continuous wire having a wire diameter of 0.1 mm or more, at least a surface layer of the wire being made of a polyester resin composition,
A continuous wire material characterized in that the polyester resin composition contains 0.5 to 10 parts by mass of an ester-based thermoplastic elastomer and 0.5 to 10 parts by mass of a polyetheramide-based polymer relative to 100 parts by mass of polyester . The cross section of the continuous wire has a two-layer structure consisting of a core and a coating surrounding the core,
The core is made of polyethylene terephthalate,
2. The continuous wire according to claim 1, wherein the coating portion is composed of a polyester resin composition containing 0.5 to 10 parts by mass of an ester- based thermoplastic elastomer and 0.5 to 10 parts by mass of a polyetheramide-based polymer, relative to 100 parts by mass of polyester. The relative viscosity of the polyester constituting the continuous wire is 1.4 or more,
the melt index (temperature 230°C, load 2.16 kg) of the ester-based thermoplastic elastomer contained in the polyester resin composition is 15 g/10 min or more;
3. The continuous wire according to claim 1, wherein the continuous wire is an ester-based thermoplastic elastomer having a durometer hardness measured in accordance with JIS K 6253 of either a Type D durometer hardness of 50 or less or a Type A durometer hardness of 95 or less.