JP2008075398A - Bag body for civil engineering work - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bag body for civil engineering work by using a fiber, including a biomass-derived polymer in at least a part not on a synthetic fiber composed only of a conventional petroleum-derived polymer, being environment-friendly such as reducing a carbon dioxide generating quantity, and capable of compensating for a defect such as abrasion resistance inferior in the biomass-derived polymer by comparing with the petroleum-derived polymer. <P>SOLUTION: This bag body for the civil engineering work is formed of knitted cloth composed of composite fiber. The composite fiber presents a core sheath shape in a cross section, and a sheath part is formed of a petroleum-derived all-purpose polymer, and a core part is formed of the biomass-derived polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bag for civil engineering work, and in particular, a bag body for a rooting construction method that is used by inputting cracked stone or lump, a bag body that is used for dewatering dredged sludge, a large soil bag, etc. It is related to the bag for civil engineering work applied to the above.

  Most of the conventional synthetic fibers are made from valuable fossil resources such as petroleum, but in recent years, fossil resources are not only concerned about the shortage of resources, but also the amount of carbon dioxide generated by society. It has a big influence. Carbon dioxide immobilization is expected to be effective in preventing global warming, and in particular, the carbon dioxide immobilization material is very attention to the Kyoto Protocol that has set the target value for carbon dioxide reduction. Use is desired. Carbon dioxide produced when biomass-derived synthetic fibers and synthetic resins are burned is originally in the air and does not increase in the atmosphere. This is called carbon neutral and tends to be regarded as important.

However, many of the synthetic fibers derived from biomass are inferior to conventional general-purpose synthetic fibers in wear resistance.
Further, for example, as a raw yarn, a composite yarn having a core-sheath type composite yarn in which a polylactic acid polymer is arranged in the core portion and an aromatic polyester resin is arranged in the sheath portion is disclosed in Patent Document 1 or the like It is disclosed. However, in patent document 1, there is no description about the specific use of this raw yarn.

  About the above-mentioned bag for civil engineering work, the form and the sewing method are conventionally known, for example in patent documents 2. However, conventional fibers generally use synthetic fibers, and are not environmentally friendly.

  In Patent Document 3, it is described that a bag for civil engineering work is produced using biomass fibers. However, the thing of patent document 3 only describes what used the polylactic acid-type fiber in the Example, and abrasion resistance is unknown only by the description.

That is, conventionally, a civil engineering bag body that is environmentally friendly and excellent in wear resistance has not been proposed.
JP 2004-353161 A JP-A-11-050428 JP 2004-183173 A

  The present invention has been made in view of such a current situation, and is not a synthetic fiber made of only a conventional petroleum-based polymer, but contains a biomass-derived polymer at least in part to reduce the amount of carbon dioxide generated, etc. An object of the present invention is to provide a civil engineering bag using fibers that are environmentally friendly and can make up for defects such as abrasion resistance that are inferior to biomass-derived polymers compared to petroleum-derived polymers.

  As a result of intensive studies to solve such problems, the present inventors have a cross-sectional shape of a core-sheath, the sheath is composed of a petroleum-based general-purpose polymer, and the core is composed of a biomass-derived polymer. The bag for civil engineering constructed using a knitted fabric using the composite fiber thus obtained has found the fact that it has excellent wear resistance, and has reached the present invention.

That is, the present invention
(1) A bag formed by a knitted fabric composed of composite fibers, wherein the composite fibers have a core-sheath shape in cross section, and the sheath part is formed of a petroleum-based general-purpose polymer. And a civil engineering bag characterized in that the core is formed of a polymer derived from biomass,

  (2) The strength of the knitted fabric is 400N or more, (1) the civil engineering bag,

  (3) The civil engineering construction bag according to (1) or (2), wherein the sheath is formed of polyethylene terephthalate;

  (4) The civil engineering bag according to any one of (1) to (3), wherein the core is formed of polylactic acid;

(5) The composite fiber is a concentric core-sheath type composite fiber in which a core part and a sheath part are arranged substantially concentrically. For civil engineering works according to any one of (1) to (4) A bag,
Is a summary.

  According to the present invention, it is not a bag for civil engineering construction of a knitted fabric using fibers made only of conventional petroleum-derived polymers or biomass-derived polymers, but contains biomass-derived polymers at least in part. It is possible to provide a civil engineering bag body that is environmentally friendly and can compensate for defects such as abrasion resistance, which is inferior to biomass-derived polymers compared to petroleum-derived polymers.

  Hereinafter, the present invention will be described in detail. The petroleum-derived polymer used for the sheath of the composite fiber constituting the civil engineering bag of the present invention is not particularly limited as long as it can be melt-spun. Specifically, polyesters typified by polyalkylene terephthalates such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate; polyamides typified by nylon 6, nylon 66, nylon 46, nylon 11 and nylon 12; polypropylene And polyolefins typified by polyethylene and polyethylene; polychlorinated polymers typified by polyvinyl chloride and polyvinylidene chloride; and polytetrafluoroethylene and copolymers thereof, and fluorine-based resins typified by polyvinylidene fluoride, etc. It is done. Of these, low cost polyesters and polyamide polymers are preferred. Moreover, since the biomass polymer mentioned later has many aliphatic polyester polymers, a polyester polymer is more preferable from a compatible surface. As the polyester-based material, polyethylene terephthalate is particularly preferable from the viewpoint of cost and handleability.

  Polyester polymers include aromatic dicarboxylic acids such as isophthalic acid and 5-sulfoisophthalic acid; adipic acid, succinic acid, suberic acid, sebacic acid, dodecane diene, in view of viscosity, thermal characteristics, and compatibility. Aliphatic dicarboxylic acids such as acids; aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol; glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, Hydroxycarboxylic acids such as hydroxypentanoic acid, hydroxyheptanoic acid and hydroxyoctanoic acid; and aliphatic lactones such as ε-caprolactone may be copolymerized.

  The biomass-derived polymer used for the core of the composite fiber constituting the civil engineering bag of the present invention is not particularly limited as long as it can be melt-spun. Specifically, polymers produced by chemically polymerizing biomass monomers such as polylactic acid, polytrimethylene terephthalate, and polybutylene succinate; and microbial production systems such as polyhydroxyalkanoates such as polyhydroxybutyrate Things can be mentioned. Of these, polylactic acid which exhibits stable heat resistance and has been relatively mass-produced is preferred.

  Examples of polylactic acid include poly D-lactic acid, poly L-lactic acid, poly D-lactic acid which is a copolymer of poly D-lactic acid and poly L-lactic acid, and a mixture of poly D-lactic acid and poly L-lactic acid (stereo Complex), a copolymer of poly D-lactic acid and hydroxycarboxylic acid, a copolymer of poly L-lactic acid and hydroxycarboxylic acid, poly D-lactic acid or poly L-lactic acid, aliphatic dicarboxylic acid and aliphatic diol A copolymer of these or a blend thereof is preferred. Polylactic acid is one in which L-lactic acid or D-lactic acid is used alone as described above, or a combination of both. However, among them, the melting point is 120 ° C. or higher and the heat of fusion is high. What is 10 J / g or more is preferable.

  The melting point of L-lactic acid and D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C., but in the case of a copolymer of D-lactic acid and L-lactic acid, the proportion of any component is about 10 mol%. Then, the melting point is about 130 ° C. When the proportion of any of the components is 18 mol% or more, the melting point is less than 120 ° C., the heat of fusion is less than 10 J / g, and almost completely amorphous properties are obtained. When such an amorphous polymer is used, it becomes difficult to heat-stretch particularly in the production process, and it becomes difficult to obtain high-strength fibers, and even if fibers are obtained, heat resistance and abrasion resistance It tends to become inferior. Therefore, as polylactic acid, the content ratio (molar ratio) of L-lactic acid and D-lactic acid represented by the content ratio of L-lactic acid and D-lactic acid when polymerizing using lactide as a raw material, that is, L / D or D / It is preferable that L is 82 or more / 18 or less. More preferably, it is 90 or more and / 10 or less, More preferably, it is 95 or more and / 5 or less.

  Among polylactic acids, the above-mentioned mixture of poly D-lactic acid and poly L-lactic acid (stereo complex) has a high melting point of 200 to 230 ° C., and when used as a bag for civil engineering work, friction heat It is difficult to be affected by the above and is particularly preferable.

  In the case of a copolymer of polylactic acid and hydroxycarboxylic acid, specific examples of hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid Etc. Of these, the use of hydroxycaproic acid or glycolic acid is preferable from the viewpoint of cost.

  In the case of a copolymer of polylactic acid, aliphatic dicarboxylic acid and aliphatic diol, the aliphatic dicarboxylic acid and aliphatic diol include sebacic acid, adipic acid, dodecanedioic acid, trimethylene glycol, 1,4-butane. Diol, 1,6-hexanediol, etc. are mentioned.

  Thus, when making polylactic acid copolymerize another component, it is preferable that polylactic acid shall be 80 mol% or more. If it is less than 80 mol%, the crystallinity of the copolymerized polylactic acid tends to be low, and the melting point is less than 120 ° C. and the heat of fusion is less than 10 J / g.

  As the molecular weight of polylactic acid, the melt flow rate measured at a temperature of 210 ° C. and a load of 21.2 N (2160 g) is 1 to 100 (g / 10 min) according to ASTM D-1238 method, which is used as an index of molecular weight. It is preferable that it is, More preferably, it is 5-50 (g / 10min). By setting the melt flow rate within this range, strength, wet heat decomposability, and wear resistance are improved.

  For the purpose of improving the durability of polylactic acid, endblockers such as aliphatic alcohols, carbodiimide compounds, oxazoline compounds, oxazine compounds, and epoxy compounds may be added to polylactic acid.

  To the above-described petroleum-based general-purpose polymer and biomass-derived polymer, various additives, thickeners, and known additives that are effective as crystal nucleating agents can be added as necessary. Specifically, carbon black, calcium carbonate, silicon oxide and silicate, zinc white, high-site clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, oxidation Aliphatic amide compounds such as zinc, antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, behenamide, aliphatic urea compounds, benzylidene sorbitol compounds, crosslinked polymer polystyrene, rosin metals Examples thereof include salt, glass fiber, and whisker. These substances may be added as they are, or may be added after performing necessary treatment as a nanocomposite. In order to achieve price performance and good physical property balance, an inorganic filler is preferably blended. Moreover, the compounding of a crystal nucleating agent is preferable.

  Furthermore, if necessary, colorants such as pigments and dyes; odor absorbers such as activated carbon and zeolite; fragrances such as vanillin and dextrin; stabilizers such as antioxidants and ultraviolet absorbers; lubricants; mold release agents; Water agent; antibacterial agent and other secondary additives can be blended.

  A plasticizer can be used in combination with a petroleum-derived general-purpose polymer or biomass-derived polymer within a range that does not impair the effects of the present invention. By using a plasticizer, it is possible to reduce the melt viscosity during heat processing, especially during extrusion processing, and to suppress a decrease in molecular weight due to shearing heat generation, etc.In some cases, an improvement in crystallization speed can also be expected. Furthermore, extensibility etc. can be provided. Although there is no limitation in particular as a plasticizer, the following can be illustrated. That is, when the polymer forming the composite fiber for the civil engineering pouch according to the present invention is an aliphatic polyester biodegradable polyester, ether plasticizers and ester plasticizers are used as plasticizers therefor. Phthalic acid plasticizers, phosphorus plasticizers, and the like are preferable, and ether plasticizers and ester plasticizers are more preferable from the viewpoint of excellent compatibility with polyester. Examples of ether plasticizers include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of ester plasticizers include esters of aliphatic dicarboxylic acids and aliphatic alcohols. Examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, sebacic acid, adipic acid, and the like. Examples of aliphatic alcohols include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-hexanol, n-octanol, 2-ethylhexanol, n-dodecanol, stearyl alcohol; ethylene glycol, 1, 2 -Dihydric alcohols such as propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, polyethylene glycol; Trimethylol propane, it may be mentioned polyhydric alcohols pentaerythritol and the like. In addition, two or more kinds of blends selected from copolymers, di-copolymers, tri-copolymers, tetra-copolymers, etc., or homopolymers, copolymers, etc. composed of combinations of two or more of the above polyethers and polyesters. Can be mentioned. Furthermore, esterified hydroxycarboxylic acid and the like can be mentioned. At least one kind of the plasticizer can be used.

  The composite fiber constituting the civil engineering pouch according to the present invention has a cross-sectional core-sheath shape, the sheath is formed of the above-described petroleum-based general-purpose polymer, and the core is the biomass described above. It must be formed of a polymer derived from it. By making such a composite fiber, the biomass-derived polymer is contained at least in part, that is, in the core, and is therefore environmentally friendly, and the core is surrounded by a sheath formed of a petroleum-derived general-purpose polymer. Since it is a structure, the bag for civil engineering work which can compensate defects, such as abrasion resistance in which a biomass origin polymer is inferior compared with a petroleum origin polymer, can be provided. Such a core-sheath composite fiber can be produced by a known method.

  The above-described composite fiber is preferably a concentric core-sheath type composite fiber in which the core portion and the sheath portion are arranged substantially concentrically. By setting it as such a structure, the petroleum-based general purpose polymer can be uniformly arranged around the core. If the eccentricity is not concentric, a thin portion is formed in the general-purpose polymer layer of the sheath, and the wear resistance may be poor at that portion.

  The civil engineering bag of the present invention is formed of a knitted fabric using the above-described composite fiber. Flexibility can be provided by being a knitted fabric. Moreover, by having flexibility, even if the construction site is in a non-land state, it can be laid following this non-land part.

  The type of the knitted fabric is not particularly limited, and a knitted structure used for industrial materials can be taken. More specifically, examples include a Russell knitting, a knotless knitting, and a knotted knitting. The selection of the knitting structure can be made as appropriate depending on the yarn used, the situation in which it is used as a civil engineering bag, and the like. Among these, a knitted fabric by Russell knitting or knotless knitting other than the knotted knitting where stress concentrates on the knot is more preferable. When linear strength is required for the bag body, a knotless knit is preferable. On the other hand, when the conditions of use are severe and part of the bag is easily damaged, or when the straight line strength of the raw yarn is relatively weak, it is necessary to have good knot strength For example, it is preferable to apply a Russell knitting composed of loops.

  The strength of the knitted fabric for use as a civil engineering bag is preferably 400 N or more when measured using each strength measurement method for the knitted fabric. As a method for measuring the strength, specifically, in the case of the Russell knitting, when the total fineness of the knitting structure is less than 5,000 dtex, the method according to 6.11.1 (a) of 6.11 of JIS L 1043 is used. In the case of 000 dtex or more, the measurement is performed at a tensile speed of 200 mm / min in accordance with 6.11.1 (b) of 6.11 of JIS L1043. On the other hand, in a knotless knitted fabric, the knitting yarn in the other direction is cut according to the direction of the original yarn (straight line) (the knitting yarn length in the other direction is cut to 1 cm) and 300 mm / min by the one-leg one-leg method Measure at the tensile speed.

  When the tension of the knitted fabric is less than 400 N, it is difficult to withstand the specifications as a civil engineering bag body, and the bag body is easily damaged. In particular, in the case of a bag body used for the root hardening method, stones or lumps collide violently, so that they are more easily damaged. In recent years, bags for beach revetments have been developed, and in that case, a knitted fabric having a strength value of 3,000 N or more may be required.

  Next, examples of the present invention will be described in detail. In addition, the measuring method and evaluation method of each physical property value in the following examples are as follows.

(1) Melting point of polylactic acid (° C.), heat of fusion (J / g)
A differential scanning calorimeter DSC-2 manufactured by Perkin Elmer was used, and the measurement was performed under the condition of a heating rate of 20 ° C./min.

(2) Content ratio (molar ratio) of L-lactic acid and D-lactic acid in polylactic acid
It measured by the high performance liquid chromatography (HPLC) method by using the equal mass mixed solution of the ultrapure water and the methanol solution of 1N sodium hydroxide as a solvent. The column used was sumichiral OA6100, and was detected by a UV absorption measuring device.

(3) Fiber fineness (dtex)
It measured according to JIS L-10153 positive fineness.

(4) Strength (fiber) (cN / dtex), elongation at break (%)
It measured according to the standard time test of JIS L-1013 tensile strength and elongation.

(5) Strong (knitted fabric) (N)
As for the knitted fabric of Russell knitted fabric, the knitted fabric having a knitted structure total fineness of less than 5,000 dtex conforms to JIS L 1043, 6.11, 6.11.1 (a), and the knitted fabric of 5,000 dtex or more is JIS. Measurement was performed at a tensile speed of 200 mm / min in accordance with 6.11.1 (b) of 6.11 of L1043.

  For unknotted knitted fabric, cut the knitting yarn in the other direction according to the direction of the original yarn (straight line) (the knitting yarn in the other direction is cut into 1 cm length), and pull at 300 mm / min by the one-leg one-leg method. Measured at speed.

(6) Abrasion resistance (residual strength after abrasion test (N))
The test was performed according to the abrasion resistance test of JIS D-4604. That is, a load of 1.25% of the strength value of the knitted fabric was suspended at one end of the sample, the other end was passed over a round file, and then fixed to the vibrating drum. Next, the vibrating drum was reciprocated by the crank and the crank arm, and the sample was reciprocated 5,000 times per repetition of 30 ± 1 times, and then the appearance of the sample was observed and judged.

(7) Implementation test In the case of a bag tailored to 3.0 x 2.0 m, 2 t of human-sized cracked stone is introduced, and in the case of a bag tailored to 4.7 x 3.2 m, 8 t Minor human-wariwari stones were introduced. And each was dropped twice from the height of 1 m toward the normal ground where gravel etc. existed, and the damage situation of the bag was observed.

Example 1
Polylactic acid (hereinafter abbreviated as “PLA”) has a melting point of 170 ° C., a heat of fusion of 38 J / g, and an L / D ratio of L-lactic acid to D-lactic acid of 98.5 / 1.5 (molar ratio). ) Was used. As the aromatic polyester, polyethylene terephthalate (hereinafter abbreviated as “PET”) copolymerized with 15 mol% of isophthalic acid having a melting point of 217 ° C. was used. Each chip was dried under reduced pressure, and then supplied to a concentric core-sheath type composite melt spinning apparatus to perform melt spinning. At this time, the copolymer PET was arranged so as to be a sheath part, and the PLA was a core part, the composite ratio (mass ratio) was 50/50, and melt spinning was performed at a spinning temperature of 240 ° C.

  The obtained composite fiber had a round cross-sectional shape with a fineness of 1430 dtex 210 filament, a tensile strength of 4.3 cN / dtex, and a cut elongation of 28.9%. Using this raw yarn, a knitted fabric was produced with a 9G Russell knitting machine so that the knitting configuration would be 13 full-scale (one side 25 mm). Two pieces of this knitted fabric cut to 3.0 m × 4.0 m are overlapped, folded in half so that it becomes about 3.0 × 2.0 m, and the side facing the folded portion is left as an opening. Then, the two sides of the side part were stitched together and tied together to form a drawstring bag. Next, a nylon rope (tensile strength of 0.75 t) having a thickness of 6 mm was inserted as a tying rope along the entire circumference of the opening part into the stitches at the bottom of the third stitch from the opening end. Similarly, a polyester rope having a thickness of 22 mm (tensile strength: 6.3 t) is inserted as a hanging rope along the entire circumference of the opening from the end of the opening to the bottom of the fifth stitch. 1 civil engineering bag was obtained.

Example 2
Using the raw yarn used in Example 1, a knitted fabric was produced with a 9G Russell knitting machine so that the knitting configuration would be 103 real (one side 75 mm). Two pieces of this knitted fabric cut to 4.7 m x 6.4 m are overlapped and folded in half so as to be about 4.7 x 3.2 m, leaving the side facing the double fold as an opening. Then, the two sides of the side part were stitched together and tied together to form a drawstring bag. Next, a nylon rope (tensile strength: 0.75 t) having a thickness of 6 mm was inserted as a tying rope along the entire circumference of the opening part into the stitches at the bottom of the third stitch from the opening end. Similarly, a polyester rope having a thickness of 30 mm (tensile strength: 12.0 t) is inserted and arranged as a suspension rope along the entire circumference of the opening part to the lower part of the stitches from the opening part. 2 civil engineering pouches were obtained.

Example 3
Using the raw yarn used in Example 1, a knotless knitted fabric in which 10 pieces were twisted with a knotless knitting machine was produced (one side 25 mm). Two pieces of this knitted fabric cut to 3.0 m × 4.0 m are overlapped, folded in half so that it becomes about 3.0 × 2.0 m, and the side facing the folded portion is left as an opening. Then, the two sides of the side part were stitched together and tied together to form a drawstring bag. Next, a nylon rope having a thickness of 6 mm (tensile strength: 0.75 t) was inserted as a tying rope along the entire circumference of the opening part into the stitches below the opening part by three stitches. Similarly, along the entire circumference of the opening, a 22 mm thick polyester rope (tensile strength: 6.3 t) is inserted and arranged as a hanging rope in the stitches at the bottom of the fifth stitch from the opening. 3 civil engineering bags were obtained.

Comparative Example 1
As the PLA, one having a melting point of 170 ° C., a heat of fusion of 38 J / g, and a content ratio of L-lactic acid to D-lactic acid of 98.5 / 1.5 (molar ratio) was used. This was dried under reduced pressure, then supplied to a melt spinning apparatus, and melt spinning was performed at a spinning temperature of 240 ° C. The obtained polylactic acid fiber had a round cross-sectional shape with a fineness of 1430 dtex, a tensile strength of 4.5 cN / dtex, and a cut elongation of 30.9%. A bag body of Comparative Example 1 was knitted and sewn in the same manner as Example 1 using this raw yarn.

Comparative Example 2
A bag body of Comparative Example 2 was obtained by knitting and sewing the raw yarn used in Comparative Example 1 in the same manner as in Example 2.

Comparative Example 3
A bag body of Comparative Example 3 was obtained by knitting and sewing the raw yarn used in Comparative Example 1 in the same manner as in Example 3.

Comparative Example 4
As the aromatic polyester, PET copolymerized with 15 mol% of isophthalic acid having a melting point of 217 ° C. was used. This was dried under reduced pressure, then supplied to a melt spinning apparatus, and melt spinning was performed at a spinning temperature of 240 ° C. The obtained fiber had a round cross-sectional shape with a fineness of 1430 dtex, a tensile strength of 4.5 cN / dtex, and a cut elongation of 27.8%. A bag body of Comparative Example 4 was knitted and sewn in the same manner as in Example 1 using this raw yarn.

Comparative Example 5
A bag body of Comparative Example 5 was obtained by knitting and sewing the raw yarn used in Comparative Example 4 in the same manner as in Example 2.

Comparative Example 6
A bag body of Comparative Example 6 was obtained by knitting and sewing the raw yarn used in Comparative Example 4 in the same manner as in Example 3.

Reference example 1
Using the raw yarn used in Example 1, a knitted fabric was produced with a 9G Russell knitting machine so that the knitting configuration would be 5 real (one side 25 mm). The bag produced in the same manner as in Example 1 was used as the bag of Reference Example 1.

表１に示すように、実施例１、２、３及び比較例４、５、６は、試験を行った全ての項目について満足するものであった。特に、実施例１、２、３は、バイオマス由来のポリマーを使用しているものの、これを芯部に配し、この芯部を鞘部の石油系由来のポリマーで覆う構成としたため、優れた耐磨耗性を示した。 Table 1 shows the results of measuring physical properties of the bags of the examples, comparative examples, and reference examples.

As shown in Table 1, Examples 1, 2, and 3 and Comparative Examples 4, 5, and 6 were satisfactory for all items tested. In particular, Examples 1, 2, and 3 use a biomass-derived polymer, but this is arranged in the core, and this core is covered with a petroleum-derived polymer in the sheath, so that it is excellent. Abrasion resistance was shown.

  Examples 1, 2, and 3 using polymers derived from biomass were environmentally friendly materials, whereas Comparative Examples 4, 5, and 6 using only copolymerized PET, which is a petroleum-based polymer. Was not.

  Comparative Examples 1, 2, and 3 using only PLA, which is a biomass-derived polymer, have poor wear resistance and could not withstand practical civil engineering applications.

  In Reference Example 1, since the strength value of the knitted fabric was low, there was a concern about practicality as a bag for civil engineering work.

Claims (5)

  A bag formed by a knitted fabric composed of a composite fiber, the composite fiber has a core-sheath shape in cross section, and the sheath is formed of a petroleum-based general-purpose polymer, A pouch for civil engineering, characterized in that the core is formed of a polymer derived from biomass.   2. The civil engineering bag according to claim 1, wherein the strength of the knitted fabric is 400 N or more.   3. The civil engineering bag according to claim 1, wherein the sheath is formed of polyethylene terephthalate.   4. The civil engineering bag according to claim 1, wherein the core is made of polylactic acid.   5. The civil engineering bag according to any one of claims 1 to 4, wherein the conjugate fiber is a concentric core-sheath type conjugate fiber in which a core portion and a sheath portion are arranged substantially concentrically. .