JP2003096649A - Safety net - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety net having reduced reduction of the net strength even if subjecting to repeated foldings and tight stretchings. SOLUTION: This safety net uses polytrimethylene-terephthalate fiber having 0.7-1.2 of intrinsic viscosity, 6-10 cN/dtex of strength, 13-25% of breaking elongation and >=85% of tensile elastic recovery, as the chain yarn and inserting yarn.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety net preferably used for construction work and the like. More specifically, it consists of Russell knitted fabric composed of chain knitting yarn and insertion yarn,
The present invention relates to a safety net having excellent elongation and recovery properties when repeatedly used and having little deterioration of net strength with time. 2. Description of the Related Art Polyester fibers have various excellent properties and are therefore increasingly used for industrial materials requiring high strength, such as safety nets. The safety net is regarded as the most important of the various properties that require the strength of the knitted fabric and its durability over time in order to ensure the safety of work. [0003] As a method of improving such net strength and its durability with time, Japanese Patent Application Laid-Open No. 3-137255 discloses an intrinsic viscosity of 0.7 or more, a breaking strength of 7.0 g / d or more, and the like.
A method using a polyester fiber having a breaking elongation of 15% or more, a toughness of 110 or more, and a hook strength of 5 g / d or more has been proposed. However, when such a fiber is formed into a Russell knitted fabric composed of a chain net yarn and an insertion yarn, the elongation behavior of the chain net yarn and the insertion yarn is different, so that the net strength is sufficiently improved for the basis weight. In addition, there is a problem in that if it is repeatedly folded at a construction site or stretched due to stretching, the elongation recoverability decreases, the net strength falls below the limit of use, and the network cannot be used. Japanese Patent Application Laid-Open No. Hei 6-240885 proposes a method of improving net strength by using polyethylene terephthalate fibers having different elongations for a chain knitting yarn and an insertion yarn and making the elongation stress behavior close to each other. . According to this method, the initial value of the net strength is certainly improved, but when repeatedly folded at the construction site or repeatedly subjected to elongation due to extension, the elongation recovery is poor, and the net strength decreases with the aging of use. There's a problem. SUMMARY OF THE INVENTION [0005] The present invention has been made in view of the above-mentioned problems of the prior art, and has an object to have excellent initial net strength, folding at a construction site, An object of the present invention is to provide a safety net that has excellent elongation recovery properties and has a small decrease in net strength even if it is repeatedly subjected to elongation due to stretching. The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that a safety net composed of a knitted fabric braided with chain yarns and insertion yarns has a The fiber used as the chain knitting yarn and the insertion yarn is polytrimethylene having an intrinsic viscosity of 0.7 to 1.2, a strength of 6 to 10 cN / dtex, an elongation at break of 13 to 25% and an elongation elastic recovery of 85% or more. The safety net which is terephthalate fiber is reached. An embodiment of the present invention will be described below in detail. The safety net according to the present invention is characterized by its center net, which is the center of the safety net product composed of a net formed by braiding a chain net yarn and an insertion yarn, an edge knitting, a tailoring yarn, a suspension net, and the like. Things. In the safety net of the present invention, the fibers used as the chain knitting yarn and the insertion yarn have an intrinsic viscosity of 0.7 to 1.
2, strength 6-10 cN / dtex, elongation at break 13-25
% And an elongation recovery of 85% or more. The polytrimethylene terephthalate, which is a component of the fiber constituting the knitted fabric of the present invention, is a polyester having a trimethylene terephthalate unit as a main repeating unit, as long as the object of the present invention is not impaired.
For example, a polyester obtained by copolymerizing the third component at 5 mol% or less based on the acid component may be used. The third component preferably used is, for example, isophthalic acid, succinic acid, adipic acid, 2,6-
Various components such as acid components such as naphthalenedicarboxylic acid and metal sulfoisophthalic acid, and glycol components such as 1,4-butanediol, 1,6-hexanediol, cyclohexanediol and cyclohexanedimethanol can be used. What is necessary is just to select suitably considering stability etc. The safety net formed by using such a polytrimethylene terephthalate fiber for a chain net yarn and an insertion yarn is surprisingly surprising in comparison with a conventional safety net using polyethylene terephthalate fiber. It has been found that the stretch recoverability after repeated use is dramatically superior. Although the mechanism of the effect of the polytrimethylene terephthalate fiber on the stretch recovery after repeated use is not clear, polytrimethylene terephthalate fiber is softer and more elastic than the polyethylene terephthalate fiber. It is presumed that it is doing. The intrinsic viscosity of the polytrimethylene terephthalate fiber used in the present invention must be in the range of 0.7 to 1.2, more preferably 0.8 to 1.0. Intrinsic viscosity of polytrimethylene terephthalate fiber is 0.7
If it is less than 10, the stretch recovery property after repeated use is not improved, and the initial net strength does not reach the use standard. When the intrinsic viscosity of the polytrimethylene terephthalate fiber exceeds 1.2, the initial network strength becomes sufficiently high, or the elongation recovery property after repeated use is poor, the network structure changes, and the network strength decreases with time. Next, the breaking strength (tensile strength) of the polytrimethylene terephthalate fiber constituting the safety net of the present invention is 6 to 10 cN / dtex, more preferably 7 to 9 cN / dtex.
cN / dtex. When the breaking strength is less than 6 cN / dtex, it is not possible to achieve the net strength reference value of 400 N or more regulated by the Temporary Industrial Association. When the breaking strength of the polytrimethylene terephthalate fiber exceeds 10 cN / dtex, the elongation recovery property after repeated use is poor, the network structure changes, and the network strength decreases with time. Next, the breaking elongation of the polytrimethylene terephthalate fiber constituting the safety net of the present invention is 13 to 2
It should be in the range of 5%, more preferably 16-20%. When the elongation at break of the polytrimethylene terephthalate fiber is less than 13%, the flexibility of the yarn is insufficient and the strength utilization rate decreases, so that the net strength of 400 N or more cannot be achieved, and the elongation recovery after repeated use. Poor nature, changes in net structure, and net strength decreases with time. If the elongation at break of the polytrimethylene terephthalate fiber exceeds 25%, the dimensional stability of the safety net itself is poor, and the safety net is not practically usable. Next, the polytrimethylene terephthalate fiber constituting the safety net of the present invention has an elongation elastic recovery of 8%.
It must be at least 5%, more preferably at least 88%. When the elongation elastic recovery of the polytrimethylene terephthalate fiber is less than 85%, the network structure is changed by repeated use, and the network strength is reduced with time. In such a polymer of polytrimethylene terephthalate fibers, a bifunctional phosphorus compound conventionally used for polyethylene terephthalate fibers is used in an amount of 0.2 to 1.0% by weight, particularly 0.1% by weight, as a phosphorus element amount. Copolymerization in the range of 3 to 0.7% by weight is preferable because flame retardancy can be improved without lowering the net strength. The above-mentioned polytrimethylene terephthalate may contain a coloring agent, a matting agent, and an ultraviolet absorber for the purpose of improving light resistance, as long as the object of the present invention is not impaired. In particular, cyanine, stilbene, phthalocyanine, anthraquinone, quinacridone, perinone,
It is preferable to add a coloring agent such as an inorganic pigment, because not only the coloring is performed but also the light resistance is improved. Further, the light resistance is preferably 45% or more. The polytrimethylene terephthalate fiber of the present invention can be produced by a conventionally known method. That is, in the polytrimethylene terephthalate polycondensation step,
If necessary, for example, a predetermined amount of the bifunctional phosphorus compound is added and copolymerized to obtain polytrimethylene terephthalate having an intrinsic viscosity of 0.6 to 0.9. Next, polytrimethylene terephthalate (hereinafter, referred to as polytrimethylene terephthalate chips) cut into pellets is subjected to solid-state polymerization by a conventional method to obtain polytrimethylene terephthalate chips having an intrinsic viscosity of 0.7 to 1.5. The obtained polytrimethylene terephthalate chip is mixed, if necessary, with a colored chip in which additives such as, for example, a coloring agent, a matting agent, and an ultraviolet absorber are blended into a master chip in advance (in the examples, as needed). We call it original arrival),
After drying, it is melted and discharged, and the discharged yarn is allowed to pass through an atmosphere heated to a temperature equal to or higher than the melting point, and then cooled and solidified with cooling air to give an oil agent in an amount of 0.05 to 1.0% by weight. The spinning speed is 500 to 1000 m / min. The obtained undrawn yarn is preheated at a temperature equal to or higher than the glass transition temperature, drawn 4.0 to 6.0 times at a draw ratio corresponding to the take-up speed of the undrawn yarn, and then drawn at 120 to 20 times.
It is obtained by heat setting and winding at a temperature of 0 ° C. The obtained drawn yarn is subjected to priming and ply-twisting to form a ply-twisted yarn having a predetermined fineness, then to a netting using a Russell knitting machine, and further at 150 to 200 ° C. for 0.5 to 3 minutes. Heat treatment to obtain safety net. The present invention will be described in more detail with reference to the following examples. Each item in the examples was measured by the following method. (1) Intrinsic Viscosity: Measured at 30 ° C. by a standard method using a phenol / tetrachloroethane = 1/1 mixed solvent. (2) Breaking strength and breaking elongation Breaking strength and breaking elongation were measured according to the method of JIS-L1013. (3) Elongation Elasticity Recovery Rate Elongation elasticity recovery rate was measured according to the method defined in JIS-L1013. After leaving the fiber for 24 hours in a room where the temperature and humidity are controlled at 20 ° C. and 65% RH, the fiber is stretched 10% at a yarn length of 20 cm and a pulling speed of 2 cm / min by a tensile tester.
Immediately after removing the weight and returning to the original gripping interval, 2c
It was pulled at a pulling speed of m / min. Then, the elongation elastic recovery rate was determined by the following equation. Elongation elastic recovery (%) = (L−L1) / L × 100 L: Elongation at 10% elongation (mm, 20 mm in this case) L1: Residual strain (mm) after the first pulling (4) ) Test length 20 cm, pulling speed 20 cm, according to the Net Strong Temporary Association
In addition, the elongation curve of only the inserted yarn measured at / min was measured by the method of (2) above by cutting the other yarn without breaking the knitting structure. (5) Net Strength Maintenance Rate (Stretching Test) The safety net was held 5 days in a vertical direction of the net, 5 m in the horizontal direction, and left outdoors for 8 days by an 8-point support method. After that, the net strength retention rate was determined from each net strength after 5 times, and the retention rate was 80% or more as a pass. (6) Flame retardancy Measured according to JIS L-1091 (D). (7) The light-resistant yarn is wound around a black panel and irradiated with ultraviolet light at 83 ° C.
After 0 hour, the strength retention of the polytrimethylene terephthalate fiber was measured. Example 1 A polytrimethylene terephthalate (PTT) chip having an intrinsic viscosity of 0.60 and copolymerized with (2-carboxyethyl) methylphosphinic acid in an amount of 0.5% by weight as a phosphorus element was used at 180 ° C. under reduced pressure. Was performed to obtain chips having an intrinsic viscosity of 0.88. Intrinsic viscosity 0.8 with the same composition as this chip
And a blue colored chip obtained by mixing 20% by weight of cyanine-based blue as a colorant in polytrimethylene terephthalate of No. 0 at a temperature of 280 ° C. at a ratio of 35: 1 and melting.
It was discharged from a spinneret having a spinning hole with a hole diameter of 0.6 mm. The discharged yarn is passed through a heating atmosphere of 300 mm in length and 300 ° C. provided under the base, and then 500 m in length.
The mixture was cooled and solidified by cooling air at 25 ° C. and 6 Nm ³ / min over a length of m, and was taken out at a speed of 800 m / min. The obtained undrawn yarn is preheated by a heating roller at 70 ° C. without being wound once, then drawn at a draw ratio of 4.8, and heat-set at 180 ° C. to obtain a 1670 dtex / 250 filament polytrimethylene terephthalate fiber. Got. The obtained polytrimethylene terephthalate fiber was subjected to a front 10020 dtex (chain knitting yarn) back 3 using a Russell knitting machine.
Knitted with 340 dtex (insertion yarn) and weighted 410 g /
After forming the knitted fabric of m ² , heat treatment was performed at 180 ° C. for 1 minute to prepare a safety net, and its performance was inspected. Table 1 shows the physical properties and network properties of the polytrimethylene terephthalate fiber. Comparative Example 1 A polyethylene terephthalate (PET) chip having an intrinsic viscosity of 0.64 and copolymerized with 0.5% by weight of (2-carboxyethyl) methylphosphinic acid as a phosphorus element was solidified at 230 ° C. under reduced pressure. Phase polymerization was performed to obtain chips having an intrinsic viscosity of 0.97. Intrinsic viscosity 0.80 with the same composition as this chip
Was mixed and melted at a temperature of 305 ° C. in a ratio of 35: 1 with polyethylene terephthalate containing 20% by weight of cyanine blue as a colorant at a temperature of 305 ° C., and discharged from a spinneret having a spinning hole with a hole diameter of 0.6 mm. . The discharged yarn is 300 mm in length provided under the base and has a temperature of 3 mm.
After passing through a heating atmosphere of 50 ° C., it is cooled and solidified with cooling air at 25 ° C. and 7 Nm ³ / min over a length of 500 mm,
It was withdrawn at a speed of 600 m / min. The obtained undrawn yarn is preheated by a heating roller at 90 ° C. without being wound once, and then drawn at a draw ratio of 5.2.
Stretch at 200 ° C and heat set at 200 ° C to 1670 dt
An ex / 250 filament polyethylene terephthalate fiber was obtained. Using the obtained polyethylene terephthalate fiber, a safety net was prepared in the same manner as in Example 1, and its performance was examined. Table 1 shows the physical properties and network properties of the polyethylene terephthalate fiber. Example 2 The copolymerization amount of (2-carboxyethyl) methylphosphinic acid was set to 0.3% by weight as a phosphorus element amount, the intrinsic viscosity of the chip after solid phase polymerization was set to 1.50, and the melting temperature To 295
C., the spinning speed was changed to 650 m / min, and the draw ratio was changed to 5.3 times, to obtain a polytrimethylene terephthalate fiber deposited in the same manner as in Example 1. Using the obtained polytrimethylene terephthalate fiber, a safety net was prepared in the same manner as in Example 1, and its performance was inspected. Table 1 shows the physical properties and network properties of the polytrimethylene terephthalate fiber. Example 3 The copolymerization amount of (2-carboxyethyl) methylphosphinic acid was set to 0.7% by weight as a phosphorus element amount, the intrinsic viscosity of the chip after solid-phase polymerization was set to 0.80, and the stretching ratio was set. A polytrimethylene terephthalate fiber which had been soaked was obtained in the same manner as in Example 1 except that 4.5 was changed to 4.5 times. Using the obtained polytrimethylene terephthalate fiber, a safety net was prepared in the same manner as in Example 1, and its performance was inspected. Table 1 shows the physical properties and network properties of the polytrimethylene terephthalate fiber. Comparative Example 2 A polytrimethylene terephthalate (PTT) chip having an intrinsic viscosity of 0.60 to which no copolymerization component of (2-carboxyethyl) methylphosphinic acid was added was used. Has an intrinsic viscosity of 0.65, does not use blue colored chips, has a melting temperature of 275 ° C., and has a spinning speed of 7
A polytrimethylene terephthalate fiber was obtained in the same manner as in Example 1, except that the stretching ratio was changed to 50 times / minute and the draw ratio was changed to 4.6 times. Using the obtained polytrimethylene terephthalate fiber, a safety net was prepared in the same manner as in Example 1, and its performance was inspected. Table 1 shows the physical properties and network properties of the polytrimethylene terephthalate fiber. [Table 1] According to the present invention, it is possible to provide a high-strength safety net in which the strength of the net is hardly reduced even if it is repeatedly subjected to folding at a construction site or extension due to extension.

Claims (1)

Claims 1. In a safety net composed of a knitted fabric knitted with a chain knitting yarn and an insertion yarn, a fiber used as the chain knitting yarn and the insertion yarn has an intrinsic viscosity of 0.7 to 0.7. 1.2, strength 6 ~
A safety net which is a polytrimethylene terephthalate fiber having 10 cN / dtex, elongation at break of 13 to 25%, and recovery of elongation elasticity of 85% or more.