Anti-static tarpolin and anti-static flexible container bag using the tarpolin

Abstract

To provide a tarpaulin having excellent antistatic property and heat resistant creep property, and a flexible container bag having excellent antistatic property, explosion proofness, and welded part heat resistance, and formed by safe high-frequency welding using this tarpaulin.SOLUTION: Provided is a tarpaulin made of an ethylene-based copolymer resin constituting a cross section of "a surface layer / a perforated fabric / a rear surface conductive layer" or a cross section of "a surface layer / a perforated fabric / an intermediate layer / a rear surface conductive layer". The perforated fabric is woven by a warp yarn group and a weft yarn group. In each of both the warp and weft yarn groups, multifilament yarns and crimped multifilament yarns are regularly and alternately arrayed, a repetition unit thereof being two to six, and are arrayed at a mix density of 15 to 30 / inch. The alternate array is a partial bulky fabric which is any one of eight types of combinations made by 1 to 4 multifilament yarns and 1 to 2 crimped multifilament yarns. The rear surface conductive layer contains conductive powder and a conductive liquid compound.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a tarpaulin base fabric used for manufacturing a flexible container bag, and a flexible container bag manufactured from this tarpaulin base fabric, and particularly relates to a tarpaulin excellent in antistatic properties and heat creep resistance, and a flexible container bag excellent in antistatic properties and weld part heat resistance using this tarpaulin.

Background Art

[0002] Flexible container bags are of a cylindrical type and a square prism type, have a filling port at the ceiling part and a discharge port at the bottom floor part, and are large containers capable of freely sealing and releasing the filling port and the discharge port. An empty flexible container bag can be folded to reduce its volume, and its handling is also easy. These flexible container bags are roughly classified into those for storing and transporting food raw materials such as flour, rice, wheat, soybeans, adzuki beans, sesame seeds, sugar, and salt, and those for storing and transporting industrial materials such as resin pellets of polyethylene and polypropylene, vinyl chloride resin pellets, and calcium carbonate powder. As the tarpaulin base fabric used for these flexible container bags, a flexible sheet in which an open-weave fabric is used as a core material and ethylene-vinyl acetate copolymer resin layers are laminated on both sides thereof is used. The reasons for using a flexible container bag made of ethylene-vinyl acetate copolymer resin are its light weight (20% to 30% lighter than that made of soft vinyl chloride resin), chemical stability (less likely to be deteriorated by the acidity or alkalinity of the filling material), safety (not contaminating the filling material with stabilizers, plasticizers, etc.), high-frequency healing property, and printability.

[0003] The production of flexible container bags generally involves joining multiple parts cut from a tarpaulin fabric and performing lap joints where the ends are welded together by high-frequency welding. In this lap joint area, since the integration is achieved substantially only by welding ethylene-vinyl acetate copolymer resin layers together, the fabric, which is essential for the strength of the tarpaulin, is in a cut state, that is, an unstable state where two pieces of fabric are adhered by an ethylene-vinyl acetate copolymer resin layer. Therefore, when heat is applied to the flexible container bag body, the ethylene-vinyl acetate copolymer resin layer softens, leading to a heat-resistant creep problem where the welded part at the bottom is damaged (thread pulling failure or peeling failure). This heat-resistant creep problem occurs particularly when filling resin pellets such as polyethylene and polypropylene that have stored heat immediately after production. When the flexible container bag is moved, the bottom of the bag bursts, causing an accident where the filled resin pellets scatter.

[0004] In order to prevent bag breakage accidents due to such heat softening, it is necessary to achieve a good balance between 1) improving the heat resistance of the ethylene-vinyl acetate copolymer resin layer and 2) improving the adhesiveness between the fabric and the ethylene-vinyl acetate copolymer resin layer. Improving the heat resistance is a well-known technique that involves using an ethylene-vinyl acetate copolymer resin with a higher degree of polymerization (a grade with a low MFR value) and a grade with a low vinyl acetate copolymer component content and that is capable of high-frequency welding. As a means of improving the adhesiveness (heat creep resistance), the applicant of the present application has proposed blending a reactive polymer having a cyclic imino ether side chain group (oxazoline group) into a polyolefin resin layer such as an ethylene-vinyl acetate copolymer resin layer (Patent Document 1), and using a bulky taslan yarn for a part of the yarns constituting the fabric (Patent Document 2) to improve the heat creep resistance. However, in the technique of Patent Document 1 that deals with a reactive polymer, there is a limitation that stable heat creep resistance cannot be obtained unless the time required for film forming is constant each time and the time until lamination with the fabric in the next process is not constant each time. Also, in the technique of Patent Document 2, in order to impart a certain degree of tear strength to the obtained tarpolin, a yarn twist is required, and the bulky effect is attenuated by applying an appropriate twist to the bulky taslan yarn, and the adhesiveness (anchor effect) with the film may fall short of expectations.

[0005] On the one hand, flexible containers made of ethylene-vinyl acetate copolymer resin are prone to generating static electricity by friction. Especially when discharging resin pellets such as polyethylene and polypropylene, or rice (free fall through the opening at the bottom of the flexible container bag), they become charged due to the friction between the resin pellets and the inner wall of the flexible container bag. As a result, resin pellets and rice grains electrostatically adhere to the inner wall of the flexible container bag, and it has been laborious to remove them. Depending on the surrounding environment, it can cause static electricity fires. Furthermore, dust such as flour and calcium carbonate during powder discharge poses a risk of inducing dust explosions. Therefore, an explosion-proof flexible container bag with antistatic performance is essential. These include flexible containers containing a polyolefin resin layer compounded with conductive carbon black (Patent Document 3), and tarpaulins composed of a resin layer containing 15 to 50 parts by mass of a polymer-type permanent antistatic agent with respect to 100 parts by mass of a resin component containing at least 10% by mass of an unsaturated ester unit (Patent Document 4), etc. However, when using the conductive carbon black in Patent Document 3, there is a possibility of a dangerous accident where an energization spark (ignition) occurs during high-frequency welding, causing burnt holes in the tarpaulin. The blending of 15 to 50 parts by mass of the polymer-type permanent antistatic agent (thermoplastic resin) in Patent Document 4 has an adverse effect on the physical properties of the polyolefin resin and also on the high-frequency weldability. Therefore, there has not yet been an explosion-proof flexible container bag (JIS C61340 4-4) that has sufficient antistatic properties, safe high-frequency weldability, and excellent heat-resistant creep properties at the joint, as well as a tarpaulin base fabric with excellent antistatic and heat-resistant creep properties for manufacturing it.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a tarpaulin excellent in antistatic properties and heat-resistant creep properties, and a flexible container bag which is antistatic, further explosion-proof (JIS C61340 4-4), and excellent in heat resistance of the welded part, obtained by safely high-frequency welding using this tarpaulin.

Means for Solving the Problems

[0008] As a result of repeated consideration and examination in view of such points, the present invention has been completed by finding that a tarpaulin obtained by providing an ethylene-based copolymer resin surface layer and an ethylene-based copolymer resin back conductive layer containing a specific conductive material with a mesh fabric in which multifilament yarns and crimped multifilament yarns are regularly arranged alternately in both the warp and weft yarn groups as a core material is excellent in antistatic properties (further explosion-proof properties) and heat-resistant creep properties.

[0009] That is, the antistatic tarp of the present invention is a tarp having a cross-section of "ethylene-based copolymer resin surface layer / openwork fabric / ethylene-based copolymer resin back conductive layer", or a tarp having a cross-section of "ethylene-based copolymer resin surface layer / openwork fabric / ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", wherein the openwork fabric is woven by warp yarn groups and weft yarn groups, and in each of the yarn groups of both warp and weft, multifilament yarns and crimped multifilament yarns are regularly arranged alternately, the repeating unit thereof is 2 to 6, and they are arranged at a mixing density of 15 to 30 per inch. The above-mentioned alternating arrangement is a partially raised fabric formed by any one of 8 combinations of the multifilament yarns (1, 2, 3, or 4) and the crimped multifilament yarns (1 or 2). It is preferable that the ethylene-based copolymer resin back conductive layer contains a conductive powder and a conductive liquid compound. By using such a partially raised fabric and an ethylene-based copolymer resin back conductive layer, the raised part (coil shape) of the crimped multifilament yarn contributes to the anchoring adhesion effect on the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer, or the ethylene-based copolymer resin intermediate layer, and the part of the multifilament yarn contributes to maintaining the tear strength of the tarp body. At the same time, a tarp excellent in antistatic property and heat creep resistance can be obtained. By using this tarp, an antistatic flexible container bag formed by safely high-frequency welding can be obtained, and further, a flexible container bag excellent in explosion-proof property (JIS C61340 4-4) and heat resistance of the welded part can be obtained. In the present specification, the multifilament yarn means a non-crimped multifilament yarn, which means a straight yarn (with twist) without raised processing.

[0010] In the antistatic tarp of the present invention, it is preferable that the conductive powder adsorbs and supports part or all of the conductive liquid compound. By adsorbing and supporting the conductive liquid compound on the conductive powder, a composite conductor with denser adhesion between the conductive powder particles can be formed, which has better stability and can obtain a high degree of antistatic property (explosion-proof property).

[0011] In the antistatic tarpolin of the present invention, it is preferable that the conductive powder is acetylene black alone or a combination of acetylene black and oil furnace carbon black. In the case of a tarpolin having a cross-section of "ethylene-based copolymer resin surface layer / woven fabric with openings / ethylene-based copolymer resin back conductive layer", the content is 2.5 to 10 parts by mass with respect to 100 parts by mass of the ethylene-based copolymer resin constituting the ethylene-based copolymer resin conductive layer, and 11 to 20 parts by mass at the explosion-proof level. In the case of a tarpolin having a cross-section of "ethylene-based copolymer resin surface layer / woven fabric with openings / ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", the content is 5 to 20 parts by mass with respect to 100 parts by mass of the ethylene-based copolymer resin constituting the ethylene-based copolymer resin conductive layer due to the thickness of the conductive layer being reduced by nearly half, and 21 to 30 parts by mass at the explosion-proof level. By means of the fine particles of the conductive powder (acetylene black, oil furnace carbon black), an antistatic tarpolin that exhibits antistatic properties and enables safe high-frequency welding that is less likely to cause spark ignition can be obtained. By using this tarpolin, it is possible to obtain an antistatic flexible container bag, and further a flexible container bag having explosion-proof properties (JIS C61340 4-4) and excellent heat-resistant creep properties of the welded part.

[0012] In the antistatic tarpolin of the present invention, the conductive liquid compound is formed by an ion pair of a cation and an anion, the cation is selected from the group consisting of imidazolium-based, imidazolinium-based, pyridinium-based, pyrazolium-based, pyrrolidinium-based, piperidinium-based, quaternary ammonium-based, phosphonium-based, sulfonium-based, and the anion has the chemical formula BF4 - , PF6 - , TaF6 - , NbF6 - , SiF6 - , AlF4 - , AlCl4 - , NO2 - , NO3 - , F - , Cl- , Br - , I - , CN - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , CF3SO2 - , CF3SO4 - , (CF3SO2)2N - , p-CH3PhSO3 - , CH3CO2 - , HSO4 - , HSO3 - , CH3SO3 - , CH3SO4 - , CF3SO3 - , (CF3SO2)3C - , C3F7CO2 - , C4F9SO3 - , (C2F5SO2)2N - , (CF3SO2)(CF3CO)N - , (CN)2N - It is preferably one selected from the above. Its content is 20 to 100% by mass based on the blending amount of the conductive powder. As a result, the conductive liquid compound can penetrate into the conductive powder structure, suppressing the loss of antistatic property due to the lubricant. By using this terpolymer, it is possible to obtain an antistatic flexible container bag formed by safely high-frequency welding, and further a flexible container bag having explosion-proof performance (JIS C61340 4-4) and excellent heat resistance of the welded part.

[0013] The antistatic tarp of the present invention is mainly composed of the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back conductive layer. This ethylene-based copolymer resin is selected from one or more of ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-acrylic acid ester copolymer resin, ethylene-methacrylic acid copolymer resin, and ethylene-methacrylic acid ester copolymer resin, and preferably has an ethylene unit content of 65 to 85% by mass. By having 15 to 35% by mass of the polar component, high-frequency welding is enabled.

[0014] The explosion-proof flexible container bag of the present invention is preferably formed by welding and integrating a plurality of parts collected from the above-mentioned antistatic tarp. This enables the production of an antistatic flexible container bag that is safely welded by high frequency, and further, a flexible container bag having excellent explosion-proof performance (JIS C61340 4-4) and heat resistance creep resistance at the welded part.

Effects of the Invention

[0015] The present invention enables the provision of a tarp excellent in antistatic property and heat resistance creep property, an antistatic flexible container bag formed by safely welding using this tarp, and further, a flexible container bag having excellent explosion-proof performance (JIS C61340 4-4) and heat resistance creep resistance at the welded part.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0017] The antistatic tarp of the present invention is a tarp that constitutes a cross-section of "ethylene-based copolymer resin surface layer / open-weave fabric / ethylene-based copolymer resin back conductive layer", or a tarp that constitutes a cross-section of "ethylene-based copolymer resin surface layer / open-weave fabric / ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer". The open-weave fabric is woven by warp yarn groups and weft yarn groups. In each of the yarn groups for both warp and weft, multifilament yarns and crimped multifilament yarns are regularly arranged alternately, with the repeating unit being 2 to 6 strands and arranged at a mixed density of 15 to 30 strands per inch. The alternating arrangement is any one of 8 combinations of multifilament yarns (1, 2, 3, or 4 strands) and crimped multifilament yarns (1 or 2 strands), which is a partially raised fabric. In the aspect where the ethylene-based copolymer resin back conductive layer contains conductive powder and a conductive liquid compound, the conductive powder is acetylene black alone or a combination of acetylene black and oil furnace carbon black, and the compounding amount is 2.5 to 10 parts by mass with respect to 100 parts by mass of the ethylene-based copolymer resin constituting the ethylene-based copolymer resin back conductive layer (in the aspect having an intermediate layer, the compounding amount is 5 to 20 parts by mass). The conductive liquid compound is formed by an ion pair of cation and anion, and the compounding amount is 20 to 100% by mass with respect to the compounding amount of the conductive powder. The ethylene-based copolymer resin is in the aspect where the content of ethylene units is 70 to 85% by mass.

[0018] The open-weave fabric used in the antistatic tarp of the present invention has a porosity of 10 to 25% and a basis weight of 125 to 325 g / m 2It is such that in each of the groups of yarns for both the warp and weft, multifilament yarns and crimped multifilament yarns are regularly arranged alternately, the repeating unit is 2 to 6, and they are arranged at a mixed density of 15 to 30 per inch. The alternating arrangement is a partial bulging fabric of any one of 8 combinations of multifilament yarns (1, or 2, or 3, or 4) and crimped multifilament yarns (1, or 2), and the part of the crimped multifilament yarns of the fabric becomes partially bulging. The above 8 repeating units, as multifilament yarns (M) and crimped multifilament yarns (W), are "MW (2-unit): 50% of the number of W", "MMW (3-unit): 33% of the number of W", "MMMW (4-unit): 25% of the number of W", "MMMMW (5-unit): 20% of the number of W", "MWW (3-unit): 66% of the number of W", "MMWW (4-unit): 50% of the number of W", "MMMWW (5-unit): 40% of the number of W", "MMMMWW (6-unit): 33% of the number of W". The repeating unit may be the same for both the warp and weft, or may be different repeating units for the warp and weft. Here, the heat-resistant creep property of the joint between those with the same numerical value of the number of W is almost the same. When the number of crimped multifilament yarns (W) exceeds the number of multifilament yarns (M), the heat-resistant creep property of the joint of the flexible container bag is maintained, but the tear strength of the flexible container bag (tarpaulin) tends to decrease. On the other hand, when the number of crimped multifilament yarns (W) is less than the number of multifilament yarns (M), the tear strength of the flexible container bag (tarpaulin) is maintained, but the heat-resistant creep property of the joint of the flexible container bag tends to decrease. Therefore, the modes of the repeating unit with a balanced tear strength and heat-resistant creep property are "MW (2-unit): 50% of the number of W", "MMW (3-unit): 33% of the number of W", "MMWW (4-unit): 50% of the number of W", "MMMWW (5-unit): 40% of the number of W", "MMMMWW (6-unit): 33% of the number of W".This repeating unit assumes that the multifilament yarn (M) and the crimped multifilament yarn (W) have the same fineness or approximate fineness (in denier or dtex units). For example, in "MMW (3 - unit)", with M (250 denier) and W (500 denier), it can have the same strength design as M (500 denier) and W (500 denier) in "MW (2 - unit)". Similarly, in "MWW (3 - unit)", with M (500 denier) and W (250 denier), it can have the same strength design as M (500 denier) and W (500 denier) in "MW (2 - unit)". However, the combined use of yarns with such different finenesses is limited to an M:W fineness ratio of about 1:2 or 2:1. The reason is that the complication of fabric design is difficult to be reflected in the tear strength and heat - resistant creep property.

[0019] The types of open-mesh fabrics include plain weave, twill weave, crepe weave, imitation gauze weave, basket weave, triaxial weave, etc. Among them, plain woven fabrics are particularly preferable because they have an excellent balance of physical properties in the warp and weft directions of the tarpaulin, and a triaxial woven fabric that can obtain an even stress dispersion effect against internal pressure load is preferable for the entire flexible container bag formed by three-dimensionally sewing a plurality of tarpaulin parts. Multifilament yarns and crimped multifilament yarns can be made of polypropylene fibers, polyethylene fibers, vinylon fibers, polyester (such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.) fibers, nylon fibers (such as 6-nylon, 6,6-nylon, 6,10-nylon, etc.), recycled fibers obtained by repolymerizing monomers obtained by depolymerizing these recycled fibers, etc., and two types of fiber species can be used as needed. In particular, a conductive carbon fiber or a conductive plating-treated fiber can be used in a part of the multifilament yarn group and arranged in a stripe shape, preferably in a grid-like conductive network configuration at a certain number interval to form a conductive structure with antistatic properties. A specific example of this is a specification in which polyester (polyethylene terephthalate) fibers are used for the multifilament yarns and the crimped multifilament yarns, and conductive carbon fiber yarns are used in a part of the multifilament yarns of the warp yarn group and the weft yarn group (at an interval of n yarns: n is an integer from 1 to 100, for example, n is 24 to 30, or 49 to 55, etc.). At this time, the conductive carbon fiber yarn may be a two-layer structure yarn having a polyester fiber multifilament yarn as the core and a conductive carbon fiber yarn (or a conductive plating-treated fiber) as the sheath, or a blended yarn of a polyester fiber multifilament and a conductive carbon fiber (or a conductive plating-treated fiber). For the tarpaulin in these weaving specifications, it is essential to provide an ethylene-based copolymer resin back conductive layer directly on the open-mesh fabric to improve the antistatic property.In addition, high-strength heat-resistant fibers such as wholly aromatic polyester fibers (polyarylate fibers), wholly aromatic polyamide fibers (polyparaphenylene terephthalamide fibers, polyparabenzamide fibers, polyparaphenylene 3,4-oxydiphenylene terephthalamide copolymer fibers, etc.) can also be used. These yarns can be arranged in a lattice pattern at regular intervals as part of the warp and weft yarn groups to form a ripstop structure that dramatically enhances the tear strength. In the open-weave fabric composed of these multifilament yarns and crimped multifilament yarns, the part of the crimped multifilament yarns becomes partially bulky to form a partially bulky fabric. A specific example of this is a specification in which polyester (polyethylene terephthalate) fibers are used for the multifilament yarns and the crimped multifilament yarns, and wholly aromatic polyamide fibers (polyparaphenylene terephthalamide fibers) are used for a part (n intervals: n is an integer from 2 to 6) of the multifilament yarns in the warp and weft yarn groups. The open-weave fabric used in the present invention can be subjected to adhesive coating, resin impregnation treatment, water repellent treatment, flame retardant treatment, etc. as required.

[0020] The multifilament yarns are twisted yarns with a fineness of 555 to 1665 dtex (twist number 100 to 300 turns / m), the filaments have a fineness of 2.2 to 11 dtex, particularly 2.2 to 5.5 dtex, and the number of filaments is preferably 50 to 757, particularly 100 to 300. Here, the twisted yarn with a fineness of 555 dtex may be a combined twist of two 277 dtex twisted yarns, and further, the twisted yarn with a fineness of 1665 dtex may be a combined twist of three 277 dtex twisted yarns. The crimped multifilament yarns are obtained by a false-twisting process of adding twist to a multifilament yarn with a fineness of 555 to 1111 dtex, a process of heat-setting this in an electric furnace (heater) to fix the twisted state, and a bulking process of forcibly untwisting the set twist to form a state where the curls are intertwined. The degree of crimp (the swollen state of the yarn diameter) can be variously controlled by combinations such as the false-twist number (T turns / m), the dry heat-setting temperature (near the softening temperature of the fiber or below), the untwist rate of untwisting the false twist (half-untwist, full-untwist), the overfeed rate, the yarn take-up speed, the twist number, the relaxation heat-treatment temperature, etc. The false-twist coefficient is "K = t × D" 1 / 2The coefficient K of the formula [t: twist number (t times / m), D: fineness (dtex)] is preferably about 4000 to 20500, and the twist number (relaxed) is preferably 50 to 150 times / m. If the twist number (relaxed) is 49 times / m or less, the strength of the crimped multifilament yarn tends to be inferior, and if it is 151 times / m or more, the bulk effect tends to disappear. For example, in the case of polyester (polyethylene terephthalate) 555 dtex (96 filaments), the false twist number T is 500 times, the false twist coefficient (K) is 11778, the dry heat setting is 220 °C, the yarn speed is 120 m / min, the overfeed rate is 5%, the twist number is 100 times / m, the relaxation heat treatment is 200 °C, and the relaxation rate is 25%. In the partial bulk fabric (openwork fabric), the part of the crimped multifilament yarn becomes partial bulk due to loops and coils, and this loop and coil have an anchoring effect of being incorporated into the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin back conductive layer, or the ethylene-based copolymer resin intermediate layer, enhancing the adhesion between the partial bulk fabric and the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer, and improving the creep resistance and heat creep resistance of the tarpolin joint part.

[0021] The ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer used in the antistatic tarpaulin of the present invention are mainly composed of an ethylene-based copolymer resin, and their thickness is about 150 to 350 μm. It is preferable that the surface layer and the back conductive layer have the same thickness, but depending on the properties of the filler, the back conductive layer can be made thinner or thicker than the surface layer. In particular, by forming the back resin layer into a two-layer structure of "ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", the conductive powder and the conductive liquid compound can be densified in the thinner conductive layer, making it easier to meet the explosion-proof standard. This ethylene-based copolymer resin is one or more selected from ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-acrylic acid ester copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-methacrylic acid ester copolymer resin, and the content of ethylene units is preferably 65 to 85% by mass. By having 15 to 35% by mass of polar components such as vinyl acetate and (meth)acrylic acid, high-frequency welding is enabled. When the content of ethylene units exceeds 85% by mass, the high-frequency weldability deteriorates due to the small amount of polar components, and it is necessary to increase the energized amperage. However, this high-output state may be dangerous for work. On the other hand, when the content of ethylene units is less than 70% by mass, the film strength of the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer decreases, and the wear resistance tends to deteriorate. As a means to improve the wear resistance of the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer, an ethylene-based copolymer resin surface layer and an ethylene-based copolymer resin conductive layer can be obtained by blending the above ethylene-based copolymer resin with an ethylene-α-olefin copolymer resin (metallocene polyethylene). The blending amount of the ethylene-α-olefin copolymer resin is preferably within a range that maintains the content of vinyl acetate, acrylic acid, acrylic acid ester, methacrylic acid, methacrylic acid ester, etc. in the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer at 15 to 30% by mass and enables high-frequency welding.Also, the melt flow rate (MFR: 190°C, load 2.16 kgf) of the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back conductive layer is preferably 0.5 to 5.0 g / 10 min, particularly preferably 1.0 to 3.5 g / 10 min. If the MFR is less than 0.5 g / 10 min, the texture of the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back conductive layer becomes hard, and the flexibility of the flexible container bag obtained is impaired. Also, if the MFR exceeds 5.0 g / 10 min, the heat resistance temperature of the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back conductive layer becomes low, deteriorating the heat resistance creep property of the joint (high-frequency welded part) of the flexible container bag obtained, and making it easy to cause a bag breakage accident due to a high-temperature filling material.

[0022] The ethylene-based copolymer resin back conductive layer contains conductive powder. As the conductive powder, acetylene black alone or a combination of acetylene black and oil furnace carbon black is used. In the case of a tarpulin constituting the cross-section of "ethylene-based copolymer resin surface layer / open-weave fabric / ethylene-based copolymer resin back conductive layer", its content is 2.5 to 10 parts by mass based on 100 parts by mass of the ethylene-based copolymer resin constituting the ethylene-based copolymer resin conductive layer, and 11 to 20 parts by mass at the explosion-proof level. In the case of a tarpulin constituting the cross-section of "ethylene-based copolymer resin surface layer / open-weave fabric / ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", its content is 5 to 20 parts by mass based on 100 parts by mass of the ethylene-based copolymer resin constituting the ethylene-based copolymer resin conductive layer due to the thickness of the conductive layer being nearly halved, and 21 to 30 parts by mass at the explosion-proof level. The primary particles of these conductive powders are particles with a particle size of 10 to 200 nm, in which 1000 to 2000 crystallites composed of 3 to 5 layers of plates with 30 to 40 carbon 6-membered rings bonded together are aggregated. The conductive powder is a structure in which 20 to 100 of these primary particles are chemically and physically bonded. Acetylene black as such a conductive powder has a primary particle size of 20 to 50 nm and a BET specific surface area of 35 to 160 m 2 / g, a structure (pH 9-10) with a DBP oil adsorption of 140-220 ml / 100 g. The oil furnace carbon black has a primary particle size of 10-100 nm and a BET specific surface area of 50-300 m 2 / g, a structure (pH 7-8) with a DBP oil adsorption of 40-200 ml / 100 g. In particular, by satisfying the property of a DBP oil adsorption of 40-220 ml / 100 g, it is possible to adsorb and carry part or all of the conductive liquid compound used in combination. The reason why acetylene black is preferred as the conductive powder in the present invention is that due to its high-purity graphite structure and long-chain structure (aggregate, agglomerate) of the structure, the sudden increase in electrical resistance (PTC phenomenon) associated with the breakage of the chain structure due to the temperature rise during high-frequency welding is less likely to occur, so it is less likely to cause spark ignition during high-frequency welding of the explosion-proof flexible container bag. Therefore, the combined use of acetylene black and oil furnace carbon black is in a mass ratio of acetylene black:oil furnace carbon black of 10:1 to 1:1. If the conductive powder is less than 2.5 parts by mass (less than 5 parts by mass in the embodiment with an intermediate layer), sufficient antistatic property (explosion-proof property) cannot be obtained, and if it exceeds 10 parts by mass (exceeds 20 parts by mass in the embodiment with an intermediate layer), spark ignition may occur during high-frequency welding. Acetylene black and oil furnace carbon black can be blended in a powder state, but in order to obtain stable and high antistatic property (explosion-proof property) by increasing the dispersion accuracy, pigment pellets highly dispersed in an ethylene-based copolymer resin can be used. This pigment pellet also contains a conductive liquid compound at the same time. Making the conductive liquid compound adsorbed in the conductive powder structure and making it a composite conductor with the conductive powder particles in close contact can obtain more stability and high antistatic property (explosion-proof property). On the other hand, when blending in a powder state, it is preferable from the viewpoints of non-scattering property, dispersibility, and high antistatic property (explosion-proof property) to make a composite conductor paste in which the conductive liquid compound is adsorbed in the conductive powder structure in advance and the conductive powder particles are in close contact.

[0023] The ethylene-based copolymer resin inner conductive layer contains a conductive liquid compound. As the conductive liquid compound, it is formed by an ion pair of a cation and an anion, and the cation is selected from the imidazolium-based (such as 1-butyl-3-methylimidazolium, 1-allyl-3-methylimidazolium, 1-butyl-2,3-dimethylimidazolium, etc.), imidazolinium-based (such as 1-butyl-3-methylimidazolinium, 1-allyl-3-methylimidazolinium, 1-butyl-2,3-dimethylimidazolinium, etc.), pyridinium-based (such as 1-butylpyridinium, 1-ethylpyridinium, 1-butyl-4-methylpyridinium, etc.), pyrazolium-based (such as 1-butylpyrazolium, 1-ethylpyrazolium, 1-butyl-4-methylpyrazolium, etc.), pyrrolidinium-based (such as 1-butyl-1-methylpyrrolidinium, 1-methyl-1-propylpyrrolidinium, etc.), piperidinium-based (such as 1-butyl-1-methylpiperidinium, 1-methyl-1-propylpyrrolidinium, etc.), quaternary ammonium-based (such as amyltriethylammonium, butyltriethylammonium, benzyldimethylethylammonium, etc.), phosphonium-based (such as tetrabutylphosphonium, tributylmethylphosphonium, tributylhexylphosphonium, etc.), sulfonium-based (such as trimethylsulfonium, triethylsulfonium, tributylsulfonium, etc.).

[0024] Also, the anion has the chemical formula BF4 - , PF6 - , TaF6 - , NbF6 - , SiF6 - , AlF4 - , AlCl4 - , NO2 - , NO3 - , F - , Cl - , Br - , I - , CN - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , CF3SO2 - , CF3SO4 -, (CF3SO2)2N - , p-CH3PhSO3 - , CH3CO2 - , HSO4 - , HSO3 - , CH3SO3 - , CH3SO4 - , CF3SO3 - , (CF3SO2)3C - , C3F7CO2 - , C4F9SO3 - , (C2F5SO2)2N - , (CF3SO2)(CF3CO)N - , (CN)2N - , is one selected from. The blending amount of these conductive liquid compounds (ion pairs) is 20 to 100% by mass with respect to the blending amount of the conductive powder. By using the conductive powder and the conductive liquid compound together, particularly by forming a conductive composite (paste) in which the conductive liquid compound is adsorbed and supported in the structure of the conductive powder, excellent antistatic properties (explosion-proof properties) can be obtained. If the blending amount of the conductive liquid compound is less than 20% by mass, the amount of the conductive liquid compound penetrating into the conductive powder structure is insufficient, and the effect of suppressing the decrease in antistatic properties (explosion-proof properties) due to the penetration of the lubricant into the conductive powder structure may be insufficient. Also, if the blending amount exceeds 100% by mass, the conductive liquid compound may bleed to the surface of the conductive layer on the back surface of the ethylene-based copolymer resin, contaminating the filler in the flexible container bag. Among the conductive liquid compounds, quaternary ammonium salts are particularly preferred. Specifically, (C2H5)5N + , (C3H7)4N + , (C4H9)4N + , (C5H 11 )4N + and other quaternary ammonium cations, and CF3SO4 - , CH3SO4 - , HSO4 - , CF3SO4 - , CH3SO3 - , HSO3 -Salts composed of anions containing sulfuric acid or sulfurous acid, such as, are included. Also, the four alkyl groups of the quaternary ammonium cation may be the same or different from each other. Among these, tetraalkylammonium hydrogen sulfates such as butyltriethylammonium and amyltriethylammonium are preferred, and tetrabutylammonium hydrogen sulfate [(C4H9)4N(HSO4)] is particularly preferred. These conductive liquid compounds are preferably adsorbed and supported on a conductive powder (acetylene black or a combination of acetylene black and oil furnace carbon black) in advance to make the space between the conductive powder particles more densely adhered, resulting in a composite conductor (paste), or granulated into concentrated pellets, from the viewpoints of non-scattering property, dispersibility, and high antistatic property (explosion-proof property). The adsorption and support can be obtained by spraying a specific amount of the conductive liquid compound onto a specific amount of the conductive powder, stirring, and then allowing it to stand at normal temperature and pressure for several hours.

[0025] If necessary, by containing 3 to 20% by mass of synthetic amorphous silica in the ethylene-based copolymer resin surface layer and / or the ethylene-based copolymer resin intermediate layer, the high-frequency weldability can be improved, and furthermore, the heat-resistant creep property can be improved. Synthetic amorphous silica (silicon dioxide) is obtained by a wet method in which sodium silicate is reacted with a mineral acid (sulfuric acid) and salts in an aqueous solution. The silanol groups (R 1 R 2 R 3Hydrous silica having water molecules hydrogen-bonded to Si-OH groups (wherein R is hydrogen, an alkyl group, etc.) and water molecules existing as hydroxyl groups contained in the silanol groups themselves as bound water, with an average aggregate particle size (by Coulter counter method) of 1 to 20 μm, preferably 2 to 10 μm, and a water content of 3 to 15% by mass, preferably 5 to 10% by mass. If the blending amount of synthetic amorphous silica is less than 3% by mass, the effect of improving heat creep resistance will be insufficient, and if the blending amount exceeds 20% by mass, it may reduce the processability and wear resistance strength of the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin intermediate layer. For this synthetic amorphous silica, one having adsorbed 10 to 50% by mass of a conductive liquid compound based on the mass of the synthetic amorphous silica is used, and the antistatic property (anti-explosion property) can be enhanced. Also, if necessary, the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back surface conductive layer can contain about 10% by mass of rubbers such as EPDM and EPM to improve wear resistance and heat creep resistance. Further, known additives such as stabilizers, fillers, coloring pigments, flame retardants, flame inhibitors, ultraviolet absorbers, light stabilizers, mildew inhibitors, antibacterial agents, antistatic agents, and crosslinking agents can be arbitrarily blended into the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back surface conductive layer.

[0026] The ethylene-based copolymer resin surface layer and the film for the ethylene-based copolymer resin back conductive layer are, for example, films formed to a thickness of about 150 to 350 μm by known methods such as the T-die extrusion method and the calendar method, and are suitable for flexible container bags. In particular, when the back resin layer has a two-layer structure of "ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", the thickness of these two layers is about 150 to 350 μm. The antistatic tarpolin that serves as the raw material for the flexible container bag is obtained by laminating these films on both sides of an open-weave fabric (partially bulging fabric). Using the pre-formed two-layer film for the front side and the back side (or the intermediate layer), it is passed through a laminator equipped with a metal hot roll / rubber roll and a heater, and the film is heat-pressed onto the open-weave fabric (partially bulging fabric) in a state of being semi-molten and softened by heating, to obtain a thickness of about 0.5 to 1.2 mm. In an embodiment including an ethylene-based copolymer resin intermediate layer, it is passed through the laminator again to laminate the ethylene-based copolymer resin back conductive layer on the ethylene-based copolymer resin intermediate layer to a thickness of about 0.5 to 1.2 mm. In these cases, by forming a partial thermal melt bridge between the films on the front side and the back side (in some cases, a two-layer structure) through the voids of the open-weave fabric, the contact surface area between the ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin back conductive layer (or the ethylene-based copolymer resin intermediate layer), and the partially bulging fabric (loops, coils) is increased. Furthermore, by incorporating loops and coils of the crimped multifilament yarns into the ethylene-based copolymer resin surface layer and the ethylene-based copolymer resin back conductive layer (or within the ethylene-based copolymer resin intermediate layer), strong anchor adhesion is achieved, and excellent heat-resistant creep properties at the joints of the flexible container bag are exhibited. The heat welding and sewing of the flexible container bag can be performed by methods such as high-frequency welder fusion method, hot air fusion method, and ultrasonic fusion method. The surface resistance value of the ethylene-based copolymer resin back conductive layer of the obtained antistatic tarpolin is, in JIS C61340 4-4 "Standard Test Methods for Specific Applications - Electrostatic Classification of Flexible Containers", 10 5 Ω to 10 8 Ω, and particularly for explosion-proof properties, 10 3 Ω to 10 4Ω is preferred. Further, in the antistatic flexible container bag and more preferably in the explosion-proof flexible container bag, the inner ethylene-based copolymer resin back conductive layer is connected to an earth wire, and it is essential to have an attached earth wire protruding outside the container bag.

[0027] Examples The present invention will be further described with reference to the following examples and comparative examples, but the present invention is not limited to the scope of these examples. 1) Heat resistance creep property of the joined body 〈Warp direction〉 The lower end of the tarpolin in the transverse direction (weft direction) and the upper end of the other tarpolin in the transverse direction (weft direction) were overlapped in parallel with a width of 9 cm, and a high-frequency welder (YTO-8A type manufactured by Yamamoto Vinita Co., Ltd.: high-frequency output 8 KW) equipped with a 9 cm width × 30 cm length weld bar (concave-convex tooth shape: convex part height 0.5 mm, 9 straight lines per inch, concave part depth 0.5 mm, 9 straight lines per inch) was used. The tarpolins were high-frequency welded and joined with an anode current of 0.8 A (energization for 5 seconds / cooling for 5 seconds). A test piece with a width of 3 cm × 30 cm length including the welded joint part with a width of 9 cm at the center in the longitudinal direction was taken from this joined body as a heat resistance creep test piece, and a creep tester (manufactured by Toyo Seiki Seisakusho Co., Ltd.: 100LDR type) was used to evaluate the heat resistance creep property in the warp direction under three conditions of 50 °C × 40 kgf load (condition 1), 55 °C × 40 kgf load (condition 2), and 60 °C × 40 kgf load (condition 3) for 24 hours. 〈Weft direction〉 The lower end of the tarpolin in the longitudinal direction (warp direction) and the upper end of the other tarpolin in the longitudinal direction (warp direction) were overlapped in parallel with a width of 9 cm, and a test piece obtained by the same procedure as the preparation of the test piece for evaluating the heat resistance creep property in the warp direction was used. The heat resistance creep property in the weft direction was evaluated for 24 hours under three conditions of 50 °C × 40 kgf load (condition 1), 55 °C × 40 kgf load (condition 2), and 60 °C × 40 kgf load (condition 3). Evaluation criteria 1: After 24 hours, the joint is in good condition without any abnormalities or defects. 2: The joint was broken before 24 hours, but the test piece did not break. 〈Record the time of breakage〉 3: The joint was broken within less than 24 hours, and the test piece was separated. 〈Record the time of breakage〉 4: The joint was broken within 1 hour, and the test piece was separated. 〈Record the time of breakage〉 Judgment of the breakage state: The joint slipped off and broke (without breaking the thread), The main body broke, etc. (with thread breakage) 2) Antistatic property of the tarp: Surface resistivity (conforming to JIS K7194) After leaving the film material piece standing for 24 hours at 23°C and 50% RH relative humidity, the surface resistivity was measured 3 times using the following resistivity meter (conforming to JIS K7194), and the average value was taken as the surface resistivity. The surface resistivity depends on the blending amount of the conductive material (conductive powder, conductive liquid compound), and the higher the blending amount, the more the explosion-proof level can be achieved. A) High resistance / resistivity meter "HiRester UP MCP-HT800 (range 10 3 ~10 14 Ω)" manufactured by Mitsubishi Chemical Analytech Co., Ltd. B) Low resistance / resistivity meter "Loresta GX MCP-T700 (range 10 -4 ~10 7 Ω)" manufactured by Mitsubishi Chemical Analytech Co., Ltd.

[0028] [Example 1] <Partially bulging fabric (open-weave fabric) 1> Plain weave fabric with a porosity of 20% due to the entanglement of warp and weft yarn groups and a mass of 136 g / m 2 M) Multifilament yarn A multifilament yarn (M) of 750 denier polyester (polyethylene terephthalate) 832 dtex (144 filaments) twisted at 150 T / m in S twist was used. This non-crimped multifilament yarn (M) has no bulging parts such as loops or coils. W) Crimped multifilament yarn 750 denier polyester (polyethylene terephthalate) 832 dtex (144 filaments), false twist number T 500 turns, false twist coefficient (K) 14422, dry heat setting at 220 °C, thread speed 120 m / min, overfeed rate 5%, after untwisting twist number 90 turns / m, relaxation heat treatment at 200 °C, relaxation rate 25% were used. This crimped multifilament yarn (W) has coiled bulging portions, and the multifilament diameter is 1.4 to 1.6 times before and after false twisting. Warp group arrangement Two multifilament yarns (M): Mixing ratio of two crimped multifilament yarns (W), repeated arrangement of "MMWW (4 - unit): number of W yarns 50%", mixing density of 19 per inch Weft group arrangement Two multifilament yarns (M): Mixing ratio of two crimped multifilament yarns (W), repeated arrangement of "MMWW (4 - unit): number of W yarns 50%", mixing density of 20 per inch <Antistatic tarp 1> Ethylene - based copolymer resin surface layer: A film with a thickness of 0.26 mm (blue) obtained by calender rolling molding of [Formulation 1] Ethylene - based copolymer resin back conductive layer: A film with a thickness of 0.22 mm (black) obtained by calender rolling molding of [Formulation 2] On the surface of the partially bulging fabric 1, a film of the ethylene - based copolymer resin surface layer (blue) and on the back, a film of the ethylene - based copolymer resin back conductive layer (black) are thermocompression - bonded between the metal hot roll / rubber roll of the laminator at 150 °C, so that the coiled bulging portions of the partially bulging fabric 1 are anchored and integrated into the ethylene - based copolymer resin surface layer and the ethylene - based copolymer resin back conductive layer. At the same time, a laminate including a bridge between the front and back films with 20% of the voids of the partially bulging fabric 1 intervening is formed, with a thickness of 0.67 mm and a mass of 649 g / m 2 of tarp 1 was obtained. The obtained tarp 1 was excellent in antistatic properties and also excellent in heat - creep resistance at the joint in the warp and weft directions. [Formulation 1] Ethylene - based copolymer resin composition Ethylene - vinyl acetate copolymer resin (EVA) (Vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass 1 part by mass of an organophosphate compound (liquid lubricant) 1.4 parts by mass of titanium oxide (white pigment) 2 parts by mass of phthalocyanine blue (blue pigment) [Formulation 2] Ethylene-based copolymer resin composition Ethylene-vinyl acetate copolymer resin (EVA) (Vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass 1 part by mass of an organophosphate compound (liquid lubricant) Acetylene black (conductive powder: particle diameter 35 nm, specific surface area 69 m 2 / g, DBP absorption 160 ml / 100 g) 8 parts by mass Tetrabutylammonium hydrogen sulfate (quaternary ammonium-based conductive liquid compound : [(C4H9)4N·(HSO4)]) 4 parts by mass ※ Use a composite paste in which 4 parts by mass of tetrabutylammonium hydrogen sulfate is adsorbed and supported on 8 parts by mass of acetylene black (acetylene B) conductive powder (the conductive liquid compound is stirred and coated on the conductive powder and allowed to stand at room temperature for 3 hours. The same applies to Examples 2 to 8 below)

[0029] [Example 2] <Partial bulky fabric (open-weave fabric) 2> Plain fabric with a porosity of 20% due to the entanglement of warp and weft yarn groups and a mass of 136 g / m 2 Using the same multifilament yarn (M) and crimped multifilament yarn (W) as in Example 1, Warp group arrangement Mixing ratio of 2 multifilament yarns (M): 2 crimped multifilament yarns (W), repeated arrangement of "MMWW (4-unit): 50% number of W yarns", mixing density of 19 yarns / inch Weft group arrangement ​​​One multifilament yarn (M): The mixing ratio of one crimped multifilament yarn (W), the repeated arrangement of "MW (unit of 2): number of W yarns 50%", and the mixing density of 20 yarns / inch were used to form a partially bulged fabric 2. <Antistatic tarp 2> Ethylene-based copolymer resin surface layer: A film with a thickness of 0.28 mm (blue) obtained by calendering and molding [Formulation 1], and an ethylene-based copolymer resin back conductive layer: A film with a thickness of 0.28 mm (black) obtained by calendering and molding [Formulation 3] were used. In the same manner as in Example 1, a tarp 2 with a thickness of 0.67 mm and a mass of 649 g / m 2 was obtained using the partially bulged fabric 2 as the base material. The obtained tarp 2 was excellent in antistatic properties and also excellent in heat-resistant creep properties at the joint parts in the warp and weft directions. [Formulation 3] Ethylene-based copolymer resin composition Ethylene-vinyl acetate copolymer resin (EVA) (vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass Organic phosphate ester compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle size 35 nm, specific surface area 69 m 2 / g, DBP absorption amount 160 ml / 100 g) 5 parts by mass Oil furnace-based carbon black (conductive powder: particle size 40 nm, specific surface area 58 m 2 / g, DBP absorption amount 168 ml / 100 g) 3 parts by mass Triethylsulfonium bis(trifluoromethanesulfonyl)imide (sulf onium-based conductive liquid compound: [(CH2CH3)3S·(CF3SO2)2 N]) 4 parts by mass ※Use a composite paste obtained by adsorbing and supporting 4 parts by mass of triethylsulfonium bis(trifluoromethanesulfonyl)imide on 5 parts by mass of acetylene black conductive powder and 3 parts by mass of oil furnace-based carbon black (F carbon black B) conductive powder (trifluoromethanesulfonyl)imide

[0030] [Example 3] <Partial pile fabric (openwork fabric) 3> Plain fabric with a porosity of 20% and a mass of 136 g / m due to the entanglement of warp and weft yarn groups 2 Using the same multifilament yarn (M) and crimped multifilament yarn (W) as in Example 1, Warp group arrangement Mixing ratio of 4 multifilament yarns (M): 2 crimped multifilament yarns (W), repeated arrangement of "MMMMWW (6 - unit): W number 33%", and mixing density of 19 / inch Weft group arrangement A partial pile fabric 3 was made with a mixing ratio of 2 multifilament yarns (M): 1 crimped multifilament yarn (W), a repeated arrangement of "MMW (3 - unit): W number 33%", and a mixing density of 20 / inch. <Antistatic tarp 3> Ethylene - based copolymer resin surface layer: A 0.28 - mm - thick film (blue) obtained by calendering and molding [Formulation 1], and ethylene - based copolymer resin back conductive layer: A 0.28 - mm - thick film (black) obtained by calendering and molding [Formulation 4]. In the same manner as in Example 1, an antistatic tarp 3 with a thickness of 0.67 mm and a mass of 649 g / m using partial pile fabric 3 as the base material was obtained. 2 The obtained tarp 3 had explosion - proof properties and excellent heat - resistant creep properties at the joints in the warp and weft directions. [Formulation 4] Ethylene - based copolymer resin composition Ethylene - vinyl acetate copolymer resin (EVA) (Vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass Organic phosphate ester - based compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle size 35 nm, specific surface area 69 m 2 / g, DBP absorption amount 160 ml / 100 g) 16 parts by mass Butylpyridinium hexafluorophosphate (pyridinium - based conductive liquid compound: [CH3(CH2)3N·PF6]) 8 parts by mass​ ※ Use a composite paste in which 4 parts by mass of butylpyridinium hexafluorophosphate is adsorbed and supported on 8 parts by mass of acetylene black conductive powder

[0031] [Example 4] <Partial bulky fabric (openwork fabric) 4> Plain fabric with a porosity of 20% due to the entanglement of warp and weft yarn groups and a mass of 136 g / m 2 Use the same multifilament yarn (M) and crimped multifilament yarn (W) as in Example 1, Warp group arrangement Mixing ratio of 3 multifilament yarns (M): 2 crimped multifilament yarns (W), repeated arrangement of "MMMWW (5 - unit): W number 40%", mixing density of 19 / inch Weft group arrangement Mixing ratio of 2 multifilament yarns (M): 1 crimped multifilament yarn (W), repeated arrangement of "MMW (3 - unit): W number 33%", mixing density of 20 / inch, and made it into partial bulky fabric 4 <Antistatic tarp 4> Ethylene - based copolymer resin surface layer: A film with a thickness of 0.28 mm (blue) obtained by calendering and molding [Formulation 1], and ethylene - based copolymer resin back conductive layer: A film with a thickness of 0.28 mm (black) obtained by calendering and molding [Formulation 5]. In the same manner as in Example 1, an antistatic tarp 4 with a thickness of 0.67 mm and a mass of 649 g / m 2 was obtained. The obtained antistatic tarp 4 had explosion - proof properties and excellent heat - resistant creep properties at the joint in the warp and weft directions. [Formulation 5] Ethylene - based copolymer resin composition Ethylene - methyl methacrylate copolymer resin (EMMA) (Methyl methacrylate content 20% by mass, MFR 2.5) 100 parts by mass Organic phosphate ester - based compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle diameter 35 nm, specific surface area 69 m 2 / g,​​ DBP absorption amount (160 ml / 100 g): 16 parts by mass 1-Butyl-3-methylimidazolium chloride (imidazolium-based conductive liquid Compound: [CH3NC3H3N(CH2)3CH3·Cl]) 8 parts by mass ※ Use a composite paste in which 4 parts by mass of 1-butyl-3-methylimidazolium chloride is adsorbed and supported on 8 parts by mass of acetylene black conductive powder

[0032]

Table 1

[0033] [Example 5] A terpolymer 5 with a thickness of 0.67 mm and a mass of 649 g / m was obtained in the same manner as in Example 1, except that the back layer (0.22 mm) of the antistatic terpolymer 1 in Example 1 was changed to "ethylene-based copolymer resin intermediate layer (0.12 mm) [Formulation 1] / ethylene-based copolymer resin back conductive layer (0.1 mm) [Formulation 6]". The obtained terpolymer 5 was excellent in antistatic properties and also excellent in heat-resistant creep properties at the joint in the warp and weft directions. 2 [Formulation 6] Ethylene-based copolymer resin composition Ethylene-vinyl acetate copolymer resin (EVA) (Vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass Organic phosphate ester compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle size 35 nm, specific surface area 69 m 2 / g, DBP absorption amount (160 ml / 100 g): 16 parts by mass Tetrabutylammonium hydrogen sulfate (quaternary ammonium-based conductive liquid compound [(C4H9)4N·(HSO4)]) 8 parts by mass ※ Use a composite paste in which 4 parts by mass of tetrabutylammonium hydrogen sulfate is adsorbed and supported on 8 parts by mass of acetylene black conductive powder

[0034] ​​​ [Example 6] The back layer (0.22 mm) of the antistatic tarpolin 2 in Example 2 was made into "ethylene-based copolymer resin intermediate layer (0.12 mm) [Formulation 1] / ethylene-based copolymer resin back conductive layer (0.1 mm) [Formulation 7]". Otherwise, it was the same as in Example 2, and a tarpolin 6 with a thickness of 0.67 mm and a mass of 649 g / m 2 was obtained. The obtained tarpolin 6 was excellent in antistatic properties and also excellent in heat-resistant creep properties at the joint in the warp and weft directions. [Formulation 7] Ethylene-based copolymer resin composition Ethylene-vinyl acetate copolymer resin (EVA) (vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass Organic phosphate ester compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle diameter 35 nm, specific surface area 69 m 2 / g, DBP absorption 160 ml / 100 g) 10 parts by mass Oil furnace carbon black (conductive powder: particle diameter 40 nm, specific surface area 58 m 2 / g, DBP absorption 168 ml / 100 g) 6 parts by mass Triethylsulfonium bis(trifluoromethanesulfonyl)imide (sulf onium-based conductive liquid compound: [(CH2CH3)3S·(CF3SO2)2 N]) 8 parts by mass ※ A composite paste in which 4 parts by mass of triethylsulfonium bis(trifluoromethanesulfonyl)imide is adsorbed and supported on 5 parts by mass of acetylene black conductive powder and 3 parts by mass of oil furnace carbon black conductive powder is used

[0035] [Example 7] The back layer (0.22 mm) of the antistatic tarpolin 3 in Example 3 was made into "ethylene-based copolymer resin intermediate layer (0.12 mm) [Formulation 1] / ethylene-based copolymer resin back conductive layer (0.1 mm) [Formulation 8]". Otherwise, it was the same as in Example 3, and a thickness of 0.67 mm and a mass of 649 g / m​​2 The obtained terpolymer 7 had excellent antistatic properties and also excellent heat-resistant creep properties at the joints in the warp and weft directions. [Formulation 8] Ethylene copolymer resin composition Ethylene-vinyl acetate copolymer resin (EVA) (Vinyl acetate content 20% by mass, MFR 2.0) 100 parts by mass Organic phosphate ester compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle diameter 35 nm, specific surface area 69 m 2 / g, DBP absorption 160 ml / 100 g) 16 parts by mass Butylpyridinium hexafluorophosphate (pyridinium-based conductive liquid compound: [CH3(CH2)3N·PF6]) 8 parts by mass ※ A composite paste in which 4 parts by mass of butylpyridinium hexafluorophosphate is adsorbed and supported on 8 parts by mass of acetylene black conductive powder is used

[0036] [Example 8] The back layer (0.22 mm) of the antistatic terpolymer 4 of Example 4 was made into "ethylene copolymer resin intermediate layer (0.12 mm) [Formulation 1] / ethylene copolymer resin back conductive layer (0.1 mm) [Formulation 9]", and otherwise the same as Example 4, and a terpolymer 8 with a thickness of 0.67 mm and a mass of 649 g / m 2 was obtained. The obtained terpolymer 8 had excellent antistatic properties and also excellent heat-resistant creep properties at the joints in the warp and weft directions. [Formulation 9] Ethylene copolymer resin composition Ethylene-methyl methacrylate copolymer resin (EMMA) (Methyl methacrylate content 20% by mass, MFR 2.5) 100 parts by mass Organic phosphate ester compound (liquid lubricant) 1 part by mass Acetylene black (conductive powder: particle diameter 35 nm, specific surface area 69 m 2 / g, DBP absorption 160 ml / 100 g) 16 parts by mass 1-Butyl-3-methylimidazolium chloride (imidazolium-based conductive liquid Compound: [CH3NC3H3N(CH2)3CH3·Cl]) 8 parts by mass ※ Using a composite paste in which 4 parts by mass of 1-butyl-3-methylimidazolium chloride is adsorbed and supported on 8 parts by mass of acetylene black conductive powder

[0037]

Table 2

[0038] [Comparative Example 1] The same as Example 1 except that the partially bulged fabric 1 of Example 1 was changed to the partially bulged fabric 5, and a tarpulin 9 with a thickness of 0.67 mm and a mass of 649 g / m 2 was obtained. <Partially bulged fabric (open weave) 5> Porosity of 20% due to the entanglement of warp and weft yarn groups, plain weave fabric with a mass of 136 g / m 2 Using the same multifilament yarn (M) and crimped multifilament yarn (W) as in Example 1, Warp group arrangement Mixing ratio of 6 multifilament yarns (M): 1 crimped multifilament yarn (W), repeated arrangement of "MMMMMMW (7 - unit): W number 14%", mixing density of 19 threads / inch Weft group arrangement Mixing ratio of 6 multifilament yarns (M): 1 crimped multifilament yarn (W), repeated arrangement of "MMMMMMW (7 - unit): W number 14%", mixing density of 20 threads / inch, and made into the partially bulged fabric 5. The obtained tarpulin 9 was excellent in antistatic properties, but inferior in heat - creep resistance at the joint in the warp and weft directions and was not suitable for actual use.

[0039] [Comparative Example 2] The same as Example 1 except that the partially bulged fabric 1 of Example 1 was changed to the partially bulged fabric 6, and a thickness of 0.67 mm and a mass of 649 g / m​2 The terpolymer 10 was obtained. <Partial raised fabric (open weave fabric) 6> Porosity of 20% due to the entanglement of warp yarn groups and weft yarn groups, mass of 136 g / m 2 Plain weave fabric Using the same multifilament yarn (M) and crimped multifilament yarn (W) as in Example 1, Warp group arrangement Using only the multifilament yarn (M), a weaving density of 19 picks per inch Weft group arrangement Using only the crimped multifilament yarn (W), a partial raised fabric 6 was obtained with a weaving density of 20 picks per inch. The obtained terpolymer 10 was excellent in antistatic properties, but was inferior in heat creep resistance at the joint in the warp direction and had a specification with problems in practicality.

[0040] [Comparative Example 3] 8 parts by mass of acetylene black (conductive powder: particle size 35 nm, specific surface area 69 m 2 / g, DBP absorption 160 ml / 100 g) in [Formulation 2] of Example 1 was replaced with 8 parts by mass of oil furnace carbon black (conductive powder: particle size 40 nm, specific surface area 58 m 2 / g, DBP absorption 168 ml / 100 g) to obtain a terpolymer 11 with a thickness of 0.67 mm and a mass of 649 g / m in the same manner as in Example 1 except for [Formulation 10]. The obtained terpolymer 11 was excellent in antistatic properties, but spark ignition occurred during high-frequency welding when preparing the heat creep resistance test piece at the joint, and it had a specification involving a risk of electric accidents. 2 The obtained terpolymer 11 was excellent in antistatic properties, but spark ignition occurred during high-frequency welding when preparing the heat creep resistance test piece at the joint, and it had a specification involving a risk of electric accidents.

[0041] [Comparative Example 4] A terpolymer with a thickness of 0.67 mm and a mass of 649 g / m was obtained in the same manner as in Example 1 except for [Formulation 11] in which 4 parts by mass of tetrabutylammonium hydrogen sulfate in [Formulation 2] of Example 1 was omitted. 2Terpolymer 12 was obtained. The obtained terpolymer 12 was excellent in heat-resistant creep property at the joint in the warp and weft directions, but its antistatic property was inferior to that of terpolymer 1. To obtain an antistatic property equivalent to that of terpolymer 1, it was uneconomical to increase the amount of acetylene black from 8 parts by mass in [Formulation 11] to 12 parts by mass.

[0042]

Table 3

Industrial Applicability

[0043] According to the present invention, it is possible to provide a terpolymer excellent in antistatic property and heat-resistant creep property, and a flexible container bag which is obtained by safely high-frequency welding using this terpolymer and which is excellent in antistatic property, further explosion-proof property (JIS C61340 4-4), and heat-resistant creep property at the welded part.

Explanation of Symbols

[0044] 1: Antistatic terpolymer 2: Partially bulging fabric (openwork fabric) 2-1: Warp 2-1-1: Multifilament yarn (M) 2-1-2: Crimped multifilament yarn (W) 2-2: Weft 2-2-1: Multifilament yarn (M) 2-2-2: Crimped multifilament yarn (W) 3―1: Ethylene-based copolymer resin surface layer 3-2: Ethylene-based copolymer resin back conductive layer 3-3: Ethylene-based copolymer resin intermediate layer 4: Heat-resistant creep test piece 5: Joint

Claims

1. A tarpolin constituting a cross-section of "ethylene-based copolymer resin surface layer / open-mesh fabric / ethylene-based copolymer resin back conductive layer", or a tarpolin constituting a cross-section of "ethylene-based copolymer resin surface layer / open-mesh fabric / ethylene-based copolymer resin intermediate layer / ethylene-based copolymer resin back conductive layer", wherein the open-mesh fabric is woven by warp yarn groups and weft yarn groups, and in each of the yarn groups of both warp and weft, multifilament yarns and crimped multifilament yarns are regularly arranged alternately, the repeating unit thereof is 2 to 6 pieces, and they are arranged at a mixed density of 15 to 30 pieces / inch. The above alternating arrangement is any one of 8 combinations of the multifilament yarn (1 piece, or 2 pieces, or 3 pieces, or 4 pieces) and the crimped multifilament yarn (1 piece, or 2 pieces), which is a partially raised fabric. The ethylene-based copolymer resin back conductive layer contains a conductive powder and a conductive liquid compound, and the conductive powder is acetylene black alone or a combination of acetylene black and oil furnace carbon black. A static dissipative tarpolin characterized by this.

2. The static dissipative tarpolin according to claim 1, wherein the conductive powder adsorbs and supports part or all of the conductive liquid compound.

3. The conductive liquid compound is formed by an ion pair of a cation and an anion, the cation is selected from one of imidazolium-based, imidazolinium-based, pyridinium-based, pyrazolium-based, pyrrolidinium-based, piperidinium-based, quaternary ammonium-based, phosphonium-based, sulfonium-based, and the anion is a chemical formula, BF ４ - 、PF ６ - 、TaF ６ - 、NbF ６ - 、SiF ６ - 、AlF ４ - 、AlCl ４ - 、NO ２ - 、NO ３ - 、F - 、Cl - 、Br - 、I - 、CN - 、AsF ６ - 、SbF ６ - 、NbF ６ - 、TaF ６ - 、CF ３ SO ２ - 、CF ３ SO ４ - 、(CF ３ SO ２ ) ２ N - 、p-CH ３ PhSO ３ - 、CH ３ CO ２ - 、HSO ４ - 、HSO ３ - 、CH ３ SO ３ - 、CH ３ SO ４ - , CF ３ SO ３ - , (CF ３ SO ２ ) ３ C - C ３ F ７ CO ２ - C ４ F ９ SO ３ - , (C ２ F ５ SO ２ ) ２ N - , (CF ３ SO ２ )(CF ３ CO)N - , (CN) ２ N - The antistatic tarpolin according to claim 1, which is one selected from the group consisting of

4. The ethylene-based copolymer resin surface layer, the ethylene-based copolymer resin intermediate layer, and the ethylene-based copolymer resin back conductive layer are mainly composed of an ethylene-based copolymer resin. This ethylene-based copolymer resin is one or more selected from ethylene-vinyl acetate copolymer resin, ethylene-acrylic acid copolymer resin, ethylene-acrylic acid ester copolymer resin, ethylene-methacrylic acid copolymer resin, ethylene-methacrylic acid ester copolymer resin, and the content of ethylene units is 65 to 85% by mass. The static dissipative tarpolin according to claim 1.

5. A static dissipative flexible container bag formed by welding and integrating a plurality of parts taken from the static dissipative tarpolin according to claim 1.

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