JP2000314061A - Safety net - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a safety net further improved in net strength and speed- reducing degree by performing a net knitting using pigmented multifilament yarns composed mainly of ethylene terephthalate constitutive unit and having respective specific levels of physical properties. SOLUTION: This safety net is obtained by performing a net knitting using pigmented multifilament yarns subjected to flame retardant/flameproof treatment; wherein the filament yarns have the following characteristics: ethylene terephthalate unit accounts for >=85 mol% of the total constitutive unit; tenacity is >=8.0 g/d, elongation is >=20%, intermediate elongation is >=7%, dry heat shrinkage is <=6%, single filament fineness is 4-35 denier, total fineness is 200-2,000 denier, and intermingling degree is >=10. This safety net contains >=70 wt.%, pref. >=80 wt.%, of the above pigmented multifilament yarns.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety net, and more particularly, to a safety net having improved strength and shock absorption.

[0002]

2. Description of the Related Art Conventionally, polyester fibers have been widely used in fields requiring high strength because of their excellent physical properties. In recent years, attempts have been made to use the safety net by taking advantage of the characteristics of polyester fiber, and the amount of use has been increasing.

In particular, in the construction industry, in order to ensure the safety of work and the safety of the surroundings, the Temporary Industrial Association sets regulations on various characteristics that the safety net should have. The safety net is required not only to withstand the drop impact force of a person or an object but also to have a small stitch from the viewpoint of preventing small objects such as bolts and nuts from falling through.

[0004] Methods for improving the net strength and impact resistance of a net are described, for example, in Japanese Patent Publication No. 61-2145 and Japanese Patent Laid-Open Publication No. 3-45766. Japanese Patent Publication No. 61-2147 discloses that the net strength and impact absorption resistance of the safety net are improved by specifying the knitted fabric structure of the safety net. However, the problem of the invention is that it is necessary to increase the basis weight when the net strength of the safety net is improved by the knitted fabric structure. For example, as regulated by the Temporary Association, to increase the net strength of the safety net to 40 kg or more, the basis weight is 450 g /
there was a need to m ² or more. As a method of increasing the basis weight, for example, a method of increasing the composition ratio of the twisted yarn or increasing the fineness of the polyester fiber can be considered. However, in any of the above methods, the basis weight increases, and as a result,
There were problems such as an increase in net weight, workability during transportation and construction, and sagging due to the weight of the net.

Japanese Patent Application Laid-Open No. 3-45766 discloses a method for obtaining a high-strength net by using a polyester fiber having specific strength, elongation, and intermediate elongation. However, the problem of the invention is that the elongation at break of the raw yarn of the polyester fiber forming the net is 14-20%
Is specified in the lower range. Looking at the relationship between the tenacity of the original yarn and the tenacity of the net in the net knitted net, the low elongation yarn has a lower tenacity retention in the knitted net than the high elongation yarn, and has the original yarn. There was a problem that the high strength could not be reflected in the net strength and a high toughness net could not be obtained.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a safety net having various characteristics such as net strength and shock absorption.

[0007]

In order to solve the above problems, the safety net of the present invention mainly has the following configuration. That is, the safety net is characterized in that 85 mol% or more of the constitutional unit is composed of ethylene terephthalate and 70 wt% or more of a multifilament satisfying the following physical properties is used. Strength ≧ 8.0 g / d Elongation ≧ 20% Intermediate elongation ≧ 7% Dry shrinkage ≦ 6% In the present invention, the intermediate elongation of the multifilament is defined as the strength and elongation (S -S) A value (%) obtained by reading the elongation corresponding to the strength of 4.5 g / d from the curve.

The following conditions (1) to (4) are preferable conditions for the safety net of the present invention, and more excellent effects can be expected by applying these conditions. (1) The fineness of the multifilament is 200 to 2000 denier, and the entanglement (CF value) is 10 or more. (2) Multifilament single fiber fineness is 4.0 to 35
Being denier. (3) The multifilament is a native yarn. (4) Being subjected to flame retardant / flame resistant treatment.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. In the multifilament used for the safety net in the present invention, it is important that 85 mol% or more of the constitutional unit is composed of ethylene terephthalate. Generally, polyamides, polyolefins, polyesters, etc. are used as general-purpose thermoplastic resins.In the safety net of the present invention, a multifilament composed of ethylene terephthalate units is used in view of strength, elongation, dimensional stability and weather resistance. Used.

[0010] The multifilament is composed of 8 structural units.
It is important that 5 mol% or more of the polyester is composed of ethylene terephthalate. In the case of a polyester having less than 85 mol% of ethylene terephthalate units, the strength and dimensional stability of the raw yarn cannot be obtained.

[0011] Polyester fiber has excellent properties of strength, elongation and dimensional stability, but also has the feature of being less susceptible to sunlight. It is the best material.

The polyester which is the material of the multifilament used in the present invention may contain a copolymer component to such an extent that physical and scientific properties are not substantially reduced. Isophthalic acid, naphthalenedicarboxylic acid,
Examples thereof include dicarboxylic acids such as diphenyldicarboxylic acid, diol components such as propylene glycol and butylene glycol, and ethylene oxide.

[0013] The strength of the multifilament used in the safety net of the present invention is 8.0 g / d or more, and preferably 8.0 g / d.
It is set to 3 g / d or more. If the strength of the multifilament is less than 8.0 g / d, when used as a safety net, the knitting strength standard value of the safety net set by the Temporary Industrial Association of 40 kg or more cannot be achieved.

The elongation of the multifilament used in the safety net of the present invention is at least 20%, preferably at least 21%. Multifilament elongation is 20%
If it is less than 1, the standard of the deceleration (G) of 15 or less in the drop test defined by the Temporary Industrial Association cannot be achieved.

Here, the deceleration (G) in the drop test will be described in more detail. The safety net, which is one of the land nets, receives the human body and it is important that the safety net does not break. At times, it is important not to give a strong shock to the human body by absorbing the falling energy of the human body. For this reason, the Temporary Industrial Association specifies that the deceleration (G) in the drop test is 15 or less.

The multifilament used in the safety net of the present invention has an intermediate elongation of 7% or more, preferably 10% or more. If the intermediate elongation of the multifilament is less than 7%, the standard of a deceleration (G) of 15 or less in a drop test defined by the Temporary Industrial Association cannot be achieved.

The net strength and deceleration (G) required for a safety net are closely related to the properties of the multifilament constituting the net, that is, the product of the strength and elongation of the filament. However, the definition of the strength and elongation in the present invention is a very important factor because the safety of the safety net is improved.

Knitting of the safety net The deceleration (G) in the drop test can be achieved by changing the knitting structure of the safety net, but the strength and elongation of the multifilament constituting the safety net can be achieved. If the intermediate elongation is out of the range specified in the present invention, the weight of the knitted fabric is greatly increased, and the cost at the time of knitting is increased.

The multifilament used in the safety net of the present invention has a dry heat shrinkage of 6% or less, preferably 5% or less. If the dry heat shrinkage of the multifilament exceeds 6%, the entire net shrinks greatly in the heat treatment and fixing after the knitting, and the net mesh becomes small, so that the desired mesh cannot be obtained.

As described above, the multifilament used in the safety net of the present invention strictly defines strength, elongation, intermediate elongation, and dry heat shrinkage. In general, polyester filaments have the property that the strength increases when the draw ratio at the time of spinning is increased, but on the contrary, the elongation decreases.
High strength and high elongation characteristics such as the multifilament used in the present invention cannot be obtained under ordinary spinning conditions. In order to satisfy both the strength and the elongation, it has been found that a high-strength, high-elongation multifilament can be obtained by optimizing the conditions of the relaxation treatment performed immediately after the high-magnification stretching. In other words, this is a method in which mechanical and thermal energy is spot-likely applied to the amorphous region of the multifilament immediately after drawing having a highly oriented fiber structure.
Specifically, by applying a relatively high temperature energy in a limited range to the yarn immediately after the completion of the drawing, applying a compressed air resistance to maintain a constant tension on the yarn, and obtaining a desired relaxation rate. This is the first multifilament characteristic obtained.

In the safety net of the present invention, a multifilament satisfying the above-mentioned properties is used in an amount of 70% by weight or more, preferably 85% by weight or more. When the use amount of the multifilament having the above characteristics is less than 70 wt%,
When used for a safety net, it is impossible to achieve the two standards of the net strength standard value of the safety net set by the Temporary Industrial Association of 40 kg or more and the deceleration (G) of 15 or less in the drop test.

The fineness of the multifilament used for the safety net of the present invention is preferably 200 to 2000 denier. In other words, the fineness of the multifilament is 2
By setting the denier to 00 to 2,000 deniers, there is no problem such as occurrence of a thinning which occurs in a yarn aligning process at the time of a net knitting or a defect in a knitted fabric thickness adjustment which is performed by aligning a yarn after knitting. And a good-quality land net can be obtained.

The multifilament used in the safety net of the present invention preferably has an entanglement (CF value) of 10 or more. That is, by setting the degree of entanglement (CF value) of the multifilament to 10 or more, problems such as catching on a guide during processing and unsuccessful unwinding from the drum around which the multifilament is wound do not occur.
A stable and good multifilament can be obtained. As a method of imparting entanglement to the filament, a conventionally known method of imparting entanglement by compressed air immediately before winding of the filament is used.

The multifilament used in the safety net of the present invention preferably has a single fiber fineness of 4.0 to 35 denier. That is, the single fiber fineness is 4.0 to 35.
By using denier, it is stable without causing problems such as drainage when the safety net is wet with water, generation of fluff in the multifilament spinning process, folding of the safety net due to increased net rigidity, poor storage stability, etc. You can get a safety net.

The multifilament used for the safety net of the present invention is preferably a soaked yarn, and the soaker is usually a cyanine type, a styrene type, a phthalocyanine type, or the like.
One or more anthraquinones, perinones, isoindolinones and the like are used, but are not limited thereto. The soaking agent is usually blended and mixed with a melted polyester chip before solid phase polymerization to obtain a colored polyester, and the chip is dried under high temperature and reduced pressure to obtain a colored master polyester. A method of blending and mixing the colored master polyester and a base non-colored polyester chip at a desired ratio and melt-spinning is generally used.

It is preferable that the safety net of the present invention has been subjected to a flame-retardant / flame-proof treatment. The flame-retardant / flame-resistant treatment may be applied to the multifilament in advance, or may be applied after the safety net has been formed. Further, after a safety net is produced using a multifilament which has been subjected to a flame retardant / flameproof treatment in advance, a flame retardant / flameproof treatment may be further performed.

As a method for treating the flame retardancy of a multifilament, for example, in a polycondensation step of polyethylene terephthalate, a bifunctional phosphorus compound is added in an amount of 0.3 to 0.8 wt% as a phosphorus element amount to a prepolymer. And a method of obtaining a polyester chip obtained by copolymerizing a phosphorus compound and melt-spinning the polyester chip to obtain a flame-retardant polyester filament. Further, a method of mixing and applying a flame retardant to a yarn-forming oil agent can also be used.

The flameproof treatment of the safety net includes, for example, a method of treating a knitted net with a phosphate ester type, a halogenated phosphate ester type, a phosphorus-containing polyol or the like, or a method of coating polyvinyl chloride. Is generally used.

[0029]

Next, the present invention will be described in detail with reference to examples. Each measurement value in the examples was measured according to the following method. [Intrinsic Viscosity (IV)] A sample (8 g) was dissolved in orthochlorophenyl (100 ml), the melt viscosity (η) was measured at 25 ° C. using an Ostwald viscometer, and the intrinsic viscosity (IV) was calculated by the following equation. IV = 0.0242η + 0.2634 [Strength / Elongation / Intermediate Elongation] The strength / elongation was measured according to JIS L 1017 using a Tensilon tensile tester manufactured by Orientec. The intermediate elongation was determined by reading the elongation corresponding to the strength of 4.5 g / d from the strength-elongation (SS) curve. [Dry heat shrinkage] Take the sample in a skein shape, 20 ° C, 65% R
0.1 g of sample after leaving in the temperature control room of H for more than 24 hours
A sample having a length L ₀ measured under a load corresponding to / d was left in an oven at 150 ° C. for 30 minutes in a non-tension state, then taken out of the oven and left in the temperature control room for 4 hours, It was calculated by the following equation from the length L ₁ measured again over the load. Dry heat shrinkage (%) = {(L ₀ −L ₁ ) / L ₀ } × 100 [Degree of confounding (CF value)] A load of 100 g is applied to a 1 m test length sample, and a 6 g hook is lowered at a speed of 1 to 1. It was lowered at a rate of 2 cm / sec, and was calculated and calculated according to the formula: Degree of confounding (CF value) = 100 (cm) / Descent distance (cm). [Net strength] Measured at an effective yarn length of 20 cm and a pulling speed of 20 cm according to the Temporary Industrial Association method. [Deceleration] According to the method of the Temporary Industrial Association, the test was carried out by an 8-point support method with a net length of 5 m and a width of 5 m. [Shrinkage at the time of heat setting] The average value A was obtained by measuring the mesh size of a net fabric sample knitted by a knitting machine by n = 20. Next, the sample was heat-set at 190 ° C. for 1 minute, the weight was measured n = 20 in the same manner as above, the average value B was obtained, the heat set shrinkage was calculated by the following equation, and the shrinkage of less than 5% was obtained. ○ ○, 5%
The thing of the above-mentioned shrinkage rate was set to x. Shrinkage (%) = {(AB) / A} × 100

(Examples 1 to 4, Comparative Examples 1 to 4) Polyethylene terephthalate having an intrinsic viscosity of 1.0 was melted at 300 ° C. and extruded from a circular discharge hole. The extruded thread,
After passing through an atmosphere having a temperature of 320 ° C. and a length of 350 mm provided immediately below the base, cold air was blown at 40 ° C./min. Next, after applying the oil agent, the yarn speed was controlled by a take-off roll to take the oil. Next, 70% of the undrawn yarn is continuously taken.
3% between two pairs of supply rolls heated and controlled to ~ 120 ° C
After stretching, the film was stretched between two pairs of heating rollers at a temperature of 200 to 250 ° C. and a stretching ratio of 4.0 to 7.0. At the same time when the stretching is completed, the contact length is 0.3 to 0.1.
While being in contact with a heating body of 6 m at a temperature of 240 to 100 ° C. 3 to 8 times, the fiber is subjected to a limited relaxation treatment at a relaxation rate of 5 to 15%. 5 kg
/ Cm ² was wound spirally while controlling the tension by blowing a spiral air to obtain a multifilament consisting of 1050 denier and 144 filaments having the properties shown in Table 1. Using a Russell knitting machine, the obtained multifilament was used for a front yarn of 6300 denier and a back yarn of 4300.
After being netted to 200 denier, 190
After heat treatment and fixing at 1 ° C. for 1 minute, a safety net with a basis weight of 410 g / m ² was obtained. The net characteristics are also shown in Table 1.
Comparative Example 5 is a multifilament obtained by using a relaxation heat treatment under ordinary spinning conditions and a net obtained therefrom. Table 1
As is clear from the results, the safety net of the present invention (Examples 1 to 4) has greatly improved network strength and deceleration as compared with the conventional safety net.

[0031]

[Table 1]

[0032]

According to the safety net of the present invention, the strength and deceleration of the net are further improved as compared with the conventional safety net, and particularly, the deceleration is extremely improved. Even when a fall accident is encountered, the impact at the time of falling can be reduced and the worker can be reliably protected.

Continued on the front page F term (reference) 4L002 AA07 AB02 AC00 AC02 CB02 EA00 EA04 FA06 4L035 BB52 BB56 BB89 BB91 CC03 CC07 DD20 EE01 EE08 EE14 EE20 FF01

Claims (5)

[Claims] 1. A safety net wherein 85 mol% or more of the constitutional unit is composed of ethylene terephthalate, and 70 wt% or more of a multifilament satisfying the following physical properties is used. Strength ≧ 8.0 g / d Elongation ≧ 20% Intermediate elongation ≧ 7% Dry heat shrinkage ≦ 6% 2. The fineness of the multifilament is 200 to 2
The safety net according to claim 1, wherein the safety net is 000 denier and the degree of confounding (CF value) is 10 or more. 3. The multifilament has a single fiber fineness of 4.
The safety net according to claim 1, wherein the safety net is 0 to 35 denier. 4. The safety net according to claim 1, wherein the multifilament is a native yarn. 5. The safety net according to claim 1, wherein a flame retardant / flame resistant treatment is applied.