JP2001207357A - Method for producing safety net - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a safety net which has excellent knitted fabric strength, excellent impact absorbability, excellent dimensional stability, and small washing shrinkage percentage, scarcely changes the touch, when washed, and is especially suitable for lease. SOLUTION: This method for producing the safety net, characterized by warp-knitting polyester filament yarns having a relative viscosity (ηrel) of >=1.50, a breaking elongation of 23 to 40%, a knot strength of >=3.5 cN/dtex, a dry heat shrinkage percent of <=15%, a single filament fineness of >=6 dtex and a total fineness of >=1,000 dtex.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a safety net used in construction work and the like.

[0002]

2. Description of the Related Art Conventionally, safety nets have been widely used in the construction industry where safety of work is important, and various properties to be provided by the safety nets are in accordance with safety net standards stipulated by the Temporary Industrial Association. , Durability, shock absorption resistance, etc., and dimensional stability, weather resistance, flame retardancy, and the like. In order to improve these characteristics, Japanese Patent Publication No. 56-128350 and Japanese Patent Publication No. 6-21
No. 405 publication. Japanese Patent Publication No. 6-21405 discloses a method for manufacturing a polyester land net mainly used for a safety net or the like, and by specifying a net knitting method, the knitted fabric strength is improved and the weight is reduced. Is described. In other words, polyester fibers are excellent in light resistance and dimensional stability, but have a problem that knitted fabric strength is hard to come out, and specific gravity is large when trying to obtain the same knitted fabric strength as knitted fabric using nylon fibers. Therefore, there is a disadvantage that the knitted fabric becomes heavy. As a method for improving the strength of the knitted fabric, Japanese Patent Publication No. 6-21405 proposes specifying the strength and intermediate elongation of the polyester fiber and specifying the knitting conditions. The net had a rough and hard texture, the knitting conditions were restricted, the knitting efficiency was poor, and the problem remained in terms of shock absorption resistance.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made in view of such circumstances, and has a strong knitted fabric, a shock absorbing property,
It is an object of the present invention to provide a method of manufacturing a safety net which is excellent in dimensional stability, has a small washing shrinkage ratio, has little change in hand by selection, and is particularly suitable for leasing.

[0004]

The present invention achieves the above object, and has a relative viscosity (ηrel) of 1.50 or more, a breaking elongation of 23 to 40%, and a knot strength of 3.5 cN / dtex or more. ,
The dry heat shrinkage is 15% or less, the boiling water shrinkage is 3% or less, the single yarn fineness is 6dtex or more, and the total fineness is 10%.
The gist of the present invention is a method for manufacturing a safety net, which comprises knitting using a polyester filament yarn having a diameter of 00 dtex or more.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The safety net according to the present invention is a net which is used in a state of being stretched horizontally in order to prevent accidents caused by a fall of an article, a work product, or an operator required for construction work such as construction work.

The polyester long fiber yarn used in the present invention is a long fiber yarn made of a polyester in which 90 mol% or more of all repeating units are ethylene terephthalate, and this polyester is preferably made of only ethylene terephthalate. When copolymerizing, isophthalic acid, adipic acid, sebacic acid and the like can be used as the third component. Further, when the relative viscosity (ηrel) of the polyester is not less than 1.50 and less than 1.50, it is difficult to obtain a fiber which simultaneously satisfies the elongation and the knot strength of the fiber. In the present invention, an ultraviolet absorber, a pigment, a flame retardant, and the like may be added during the polymerization or spinning of the polyester. When a colored yarn is obtained by adding a pigment, a cyanine-based, styrene-based, phthalocyanine-based, anthraquinone-based, isoindolinone-based, or quinochloridone-based organic or inorganic pigment can be used as the pigment. One or two of these pigments
The desired color tone can be obtained using more than one species.

The fiber properties of the polyester filament yarn used in the present invention have a cut elongation of 23 to 40%, a knot strength of 3.5 cN / dtex or more, a dry heat shrinkage of 15% or less, and a single yarn fineness of not more than 15%. 6dtex or more, total fineness is 1000dtex
That is all. Polyester long fiber yarn has an elongation of 23.
When the elongation at break is less than 23%, the flexibility of the yarn is insufficient, the strength utilization rate of the yarn is reduced, the strength of the knitted fabric is insufficient, and the shock absorption is reduced. . Cutting elongation is 4
If it exceeds 0%, the dimensional stability of the knitted fabric decreases. The strength at the time of measuring the elongation at break is preferably 6 cN / dtex or more. The knot strength of polyester filament yarn is 3.5 cN / dte
If it is not less than x and less than 3.5 cN / dtex, sufficient knitted fabric strength cannot be obtained.

[0008] As the heat shrinkage property of the polyester-based long fiber yarn, it is necessary that the dry heat shrinkage is 15% or less. The polyester long fiber yarn used as the knitting yarn needs to have heat shrinkage so that the shrinkage stress works efficiently when knitting and then heat setting to tighten the stitch.
If the dry heat shrinkage is large, the net weight of the net increases due to shrinkage during heat setting, and if it is too small, the stitches will not be tightened. Therefore, the dry heat shrinkage is preferably 3 to 10%. As for the shrinkage property, in order to reduce shrinkage during washing when the safety net is washed and reused, a smaller boiling water shrinkage ratio is advantageous, and the polyester filament yarn used in the present invention is used. Is preferably not more than 3%.

The fineness of the polyester long fiber yarn constituting the net is such that the single yarn fineness is 6 dtex or more and the total fineness is 1000 dtex or more. If the single-filament fineness is less than 6 dtex, the net may be quickly deteriorated by being exposed to sunlight, wind and rain, or may be quickly deteriorated by friction with earth and sand used at a construction site or the like. If the total fineness is less than 1000 dtex, the net-making efficiency becomes poor. Note that the total fineness is a fineness in a state where a net is formed, and may be less than 1000 dtex in a state where it is supplied at the time of making a net, or a means such as a uniform supply may be used.

[0010] The safety net of the present invention is knitted with a warp knitting machine of a Russell knitting machine using the above-mentioned polyester long fiber yarn as a knitting yarn such as a chain knitting yarn or an insertion yarn, and finishing the obtained knitted fabric. It can be obtained by processing. The shape of the stitch of the net may be any of a square shape, a hexagonal shape, a tortoiseshell shape and the like, and the size of the stitch may be selected and determined according to the application field. In the finishing processing, it is sufficient to perform processing for imparting characteristics according to the application, such as dyeing, resin processing for abrasion prevention, and imparting flame retardancy. Utilizing the heat shrinkage property of the fiber yarn, it is effective for tightening the stitch to finish a stable and strong net.

[0011]

According to the present invention, since the elongation of the polyester filament yarn constituting the net is large, the toughness of the yarn is increased, the impact absorbing power of the net is increased, and the stitch is firmly formed due to the heat shrinkage property. In addition, a tight knitted fabric can be obtained which has the strength as a safety net.

[0012]

Next, the present invention will be described in detail with reference to examples. The evaluation in the examples was performed by the following method. (1) Relative viscosity (ηrel) of polyester yarn A sample was dissolved at a temperature of 130 ° C in a ratio of 1.2 g of a sample to 100 ml of orthofluorophenol, and measured at an ambient temperature of 25 ° C using an Ostwald viscometer. (2) Tensile strength and elongation of polyester yarn Measured according to JIS L10137,5. (3) Knot strength of polyester yarn Measured according to JIS L1013 7,6. (4) Measure the initial length a of the sample under a load of 0.1 g / dtex of the dry heat shrinkage of the polyester yarn, leave the sample in an oven at 180 ° C. for 30 minutes in a tensionless state, and again apply a load of 0.1 g / dtex. The length b of the sample was measured, and the dry heat shrinkage C was calculated by the following equation. C (%) = ((ab) / a) × 100 (5) Knitted fabric strength The knitting strength was measured by a one-line and two-section method of a test method of a mesh yarn specified by the Japan Temporary Association. According to the provisions of the Temporary Industrial Association, if the length of one side of the mesh is 1.5 cm, the strength of the net yarn is 40 kg (392 N) or more. (6) Wear Resistance According to JIS D4604, the retention rate of the knitted fabric strength before and after the belt friction was performed 2500 times with a load of 49 N was calculated. (7) Weather resistance The retention rate of the knitted fabric strength before and after irradiation for 1000 hours at 83 ° C. with a carbon fade meter was calculated according to JIS L0842. (8) Drop test The safety test was performed in accordance with the performance test method using a falling weight of the safety net specified by the Temporary Industrial Association. According to the provisions of the Temporary Industrial Association, a case where a specified weight is dropped from a height of 0.75 times the length of the net and the weight does not fall through is regarded as acceptable.

Example 1 Polyethylene terephthalate having a relative viscosity of 1.56 was melt-spun and drawn, having a strength of 5.9 cN / dtex and an elongation of 26.2.
%, Knot strength 4.0 cN / dtex, dry heat shrinkage 10%, boiling water shrinkage 2%, single yarn fineness 8.7 dtex, total fineness 16
Sixty polyester filament yarns having 70 dtex and 192 filaments are drawn and fed as a chain knitting yarn, and two drawn and fed as insertion yarns.
Knit a square stitch net of 1.6 cm with 9 courses, 270 stitches / width, and heat-treat at 180 ° C for 1 minute with a tenter. A safety net of the present invention having a length of 0.5 mm and a net length of 5 m was obtained.

Comparative Example 1 Polyethylene terephthalate having a relative viscosity of 1.56 was melt-spun and drawn in place of the polyester filament yarn used in Example 1, and had a strength of 7.5 cN / dtex and an elongation of 1
5.3%, knot strength 3.5 cN / dtex, dry heat shrinkage 15
%, A boiling water shrinkage of 5%, a single yarn fineness of 8.7 dtex, a total fineness of 1670 dtex, and a polyester long fiber yarn having 192 filaments were used.

Comparative Example 2 Polyethylene terephthalate having a relative viscosity of 1.56 was melt-spun and drawn in place of the polyester filament yarn used in Example 1, and the strength was 5.9 cN / dtex and the elongation was 2
0.0%, knot strength 3.6 cN / dtex, dry heat shrinkage 10
%, A boiling water shrinkage rate of 2%, a single fiber fineness of 8.7 dtex, a total fineness of 1670 dtex, and a polyester long fiber yarn having 192 filaments were obtained in the same manner as in Example 1 to obtain a net of a comparative example.

Comparative Example 3 Polyethylene terephthalate having a relative viscosity of 1.45 was melt-spun and drawn in place of the polyester filament yarn used in Example 1, having a strength of 5.0 cN / dtex and an elongation of 2
5.2%, knot strength 3.4cN / dtex, dry heat shrinkage 10
%, A boiling water shrinkage rate of 2%, a single fiber fineness of 8.7 dtex, a total fineness of 1670 dtex, and a polyester long fiber yarn having 192 filaments were obtained in the same manner as in Example 1 to obtain a net of a comparative example.

Comparative Example 4 Polyethylene terephthalate having a relative viscosity of 1.56 was melt-spun and drawn in place of the polyester filament yarn used in Example 1, having a strength of 6.0 cN / dtex and an elongation of 2
6.2%, knot strength 3.9cN / dtex, dry heat shrinkage 10
%, A boiling water shrinkage of 2%, a single yarn fineness of 5.2 dtex, a total fineness of 1670 dtex and a filament length of 320 were used to obtain a comparative example net in the same manner as in Example 1. Table 1 shows the evaluation results of the nets of Example 1 and Comparative Examples 1 to 4.

[0018]

[Table 1]

As is clear from Table 1, the safety net according to the present invention has a sufficient strength of the knitted fabric as a safety net even if the strength is small, and has a shock absorption resistance enough to pass the drop test. Comparative Example 1 using a yarn having a low elongation is excellent in abrasion resistance and weather resistance. In Comparative Example 2 using the strip, the knitted fabric strength was small, the shock absorption resistance was small, and the property required for a safety net was not provided.
Comparative Example 3 using a yarn having a small relative viscosity of the original yarn and Comparative Example 4 using a yarn having a small single yarn fineness were inferior in abrasion resistance and weather resistance.

[0020]

The safety net according to the present invention has a strong knitted fabric,
It is excellent in shock absorption resistance and dimensional stability, has a small washing shrinkage ratio, and has little change in texture due to washing, and is useful as a safety net particularly suitable for leasing.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2E184 JA03 KA09 KA11 KA15 KA17 LA33 LC05 4L002 AA07 AB02 AB04 AC00 AC02 CA03 CB02 EA05 FA06

Claims (1)

[Claims] 1. A relative viscosity (ηrel) of 1.50 or more, a breaking elongation of 23 to 40%, a knot strength of 3.5 cN / dtex or more,
Dry heat shrinkage of 15% or less and single yarn fineness of 6 dtex
A method for producing a safety net, comprising: performing warp knitting using a polyester filament yarn having a total fineness of 1000 dtex or more.