JP2008014098A - Filter for drain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter for drain capable of reducing any load to the environment and of offering excellent characteristics required such as a decreased load to the environment, good workability, excellent dynamic characteristics, and the like. <P>SOLUTION: The filter for drain is made of an unwoven cloth of thermoplastic filaments which is characteristic in that the unwoven cloth contains thermoplastic filaments made of blended polymers of aliphatic polyester and polyamide. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a drain filter, which includes a thermoplastic filament made of a blend polymer of an aliphatic polyester and a polyamide.

The vertical drain method is a method for the purpose of promoting consolidation of soft and viscous ground. It is intended to enhance the consolidation of the discharged ground. Among them, typical methods include a sand drain method using sand as a drain material, and a paper drain method using paper as a drain material. However, since the paper drain method uses paper as a drain material, there is a problem that if it is immersed in water for a long time, its tensile strength is reduced and the paper is cut. In order to improve this, the paper drain material has been changed from paper to plastic, and most paper drains are now transitioning to plastic board drains. However, when plastic drains are used, the shield is implemented after ground improvement. There is a problem that the drain material gets entangled with the cutting edge at the time of construction, or the ground excavation work is hindered. In order to solve such a problem, a board drain made of a biodegradable resin has been proposed. For example, Patent Document 1 includes a net-like structure made of a cellulose-based material such as pulp, cotton, or hemp, a protein material such as wool or silk, and a natural degradable material such as polylactic acid, and these naturally decomposable materials. A naturally degradable drain comprising a combination with paper or non-woven fabric is disclosed. Further, Patent Document 2 discloses a board drain in which a plate-shaped core material and a filter material are laminated and integrated in a sheet shape or combined, and all of the constituent materials are biodegradable materials. Has been. Furthermore, Patent Document 3 discloses a drain material characterized in that the plate-like core material and the sheet-like water permeable material in which parallel grooves are formed are made of a biodegradable resin.

However, in any of the methods, the drain filter material has insufficient mechanical properties such as strength, elongation, and tear strength, and there is a problem that the filter material is easily damaged during construction or during use of the drain material.
JP 2004-245004 A JP 2004-1000044 A JP 2002-266340 A

In view of the background of the above-described conventional technology, the present invention is an alternative to the filter material used in conventional paper drains and plastic board drains, and has low environmental burden and excellent characteristics such as workability and mechanical characteristics. We will provide a drain filter.

In order to solve the above problems, the present invention employs the following means. That is, the drain filter of the present invention is a drain filter composed of a thermoplastic filament nonwoven fabric, wherein the nonwoven fabric includes a thermoplastic filament composed of a blend polymer of aliphatic polyester and polyamide. It is.
Preferred embodiments of the drain filter of the present invention are as follows. That is,
(1) wherein a single fiber fineness of the thermoplastic filaments consisting of a blend polymer 1-8 dtex, basis weight of the nonwoven fabric is 20 to 200 g / m ^2, and the basis weight and the tensile strength of the nonwoven fabric, the elongation at break And the tear strength satisfies the following formulas (I) and (II):
200 ≧ Y × Z / X ≧ 80 (I)
T / X ≧ 0.9 (II)
However, X: nonwoven fabric basis weight (g / m ² ), Y: tensile strength (N / 5 cm) of nonwoven fabric, Z: tensile elongation (%) of nonwoven fabric, T: tear strength of nonwoven fabric (2) Water permeability coefficient is 1. 0 × 10 ⁻¹ cm / sec or more,
(3) The weight ratio of aliphatic polyester: polyamide of the blend polymer is 50:50 to 95: 5,
(4) In the cross-sectional direction of the thermoplastic filament made of the blend polymer, the polyamide component is finely dispersed with an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex,
(5) The aliphatic polyester is polylactic acid, and the polyamide is nylon 6.
(6) The thermal bonding between the thermoplastic filaments constituting the nonwoven fabric is partially made in a range of 5 to 50% with respect to the total area of the nonwoven fabric,
It is.

  According to the present invention, it is possible to provide a drain filter having excellent mechanical properties such as tensile strength, tensile elongation, and tear strength while including aliphatic polyester, which is a raw material with low environmental load, as one of the main components. it can.

  The present invention, which has a low drain on the environment, that is, a drain filter excellent in required properties such as workability and mechanical properties, has been intensively studied, and the nonwoven fabric constituting the drain filter is made of aliphatic polyester and polyamide. As a result of making a thermoplastic filament made of a blend polymer of a specific combination, it was found that this problem could be solved all at once.

  The drain filter of the present invention is composed of a thermoplastic filament nonwoven fabric, and a thermoplastic filament composed of a blend polymer in which aliphatic polyester and polyamide are blended is used as the thermoplastic filament constituting the thermoplastic filament nonwoven fabric. However, it has characteristics.

  The aliphatic polyester is not particularly limited as long as it is a biodegradable aliphatic polyester. For example, polylactic acid, polyglycolic acid, polyhydroxybutyrate, polyhydroxybutyrate valerate, or a copolymer or modified product thereof. Can be used alone or in combination. Of these, polylactic acid is most preferable because it has good spinnability and mechanical properties, and can be synthesized from plant-derived starch, and therefore has little environmental impact. As such polylactic acid, poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, or a blend thereof (including a stereo complex) is preferable. . The weight average molecular weight of such polylactic acid is preferably 50,000 to 300,000, more preferably 100,000 to 300,000. When the weight average molecular weight is less than 50,000, the strength of the fiber tends to be low, and when the weight average molecular weight exceeds 300,000, the spinnability of the polymer extruded from the nozzle is poor because the viscosity is high, It becomes difficult to draw at high speed, and ultimately it becomes an undrawn state, and there is a tendency that sufficient fiber strength cannot be obtained.

  Further, the aliphatic polyester used in the present invention is preferably one in which a part or all of the carboxyl groups at the molecular chain terminals are end-capped with a terminal blocking agent. When a part or all of the carboxyl groups at the end of the molecular chain of the aliphatic polyester are end-capped, a decrease in strength of the filament and further the sheet due to hydrolysis is suppressed. The terminal carboxyl group concentration of the aliphatic polyester is preferably 0 to 20 equivalents / ton, more preferably 0 to 15 equivalents / ton, and more preferably 0 to 10 equivalents / ton by adding a terminal blocking agent. Is more preferable. Here, the carboxyl group terminal concentration of the aliphatic polyester was determined by dissolving a precisely weighed sample in o-cresol (5% water), adding an appropriate amount of dichloromethane to this solution, and titrating with 0.02 N KOH methanol solution. Can be obtained.

  The endblocker for the aliphatic polyester used in the present invention is not limited at all, but carbodiimide compounds and glycidyl-modified compounds having isocyanuric acid as a basic skeleton are preferable. The addition amount of these end-capping agents is preferably in the range of 0.05 to 10 wt%, more preferably in the range of 0.1 to 7 wt%, with respect to the aliphatic polyester.

Although it does not specifically limit as a carbodiimide compound used as a terminal blocker of aliphatic polyester in this invention, When a monocarbodiimide compound is used, 5% weight reduction temperature (henceforth T5 _% is shown. ) Is preferably a monocarbodiimide compound having a temperature of 170 ° C. or higher, and more preferably, T _5% is a monocarbodiimide compound having a temperature of 190 ° C. or higher. When T _5% of the monocarbodiimide compound is less than 170 ° C., the monocarbodiimide compound is decomposed and / or vaporized during spinning, which tends to increase yarn breakage and deteriorate product quality, which is not preferable. Furthermore, the monocarbodiimide compound is not preferable because it does not effectively react and act on the carboxyl group terminal of the aliphatic polyester and a sufficient effect of improving hydrolysis resistance cannot be obtained. Here, the 5% weight loss temperature is a sample weight of about 10 mg measured by a “TG-DTA2000S” TG-DTA measuring machine manufactured by MACSCIENCE, at a temperature rising rate of 10 ° C./min in a nitrogen atmosphere. This is the temperature obtained as the temperature when the weight is reduced by 5% with respect to the sample weight before the start of measurement.

  Examples of the monocarbodiimide compound that can be used as a terminal blocking agent in the present invention include, for example, N, N′-di-2,6-diisopropylphenylcarbodiimide, N, N′-di-2,6-di-tert. . -Butylphenylcarbodiimide, N, N'-di-2,6-diethylphenylcarbodiimide, N, N'-di-2-ethyl-6-isopropylphenylcarbodiimide, N, N'-di-2-isobutyl-6 Isopropylphenylcarbodiimide, N, N′-di-2,4,6-trimethylphenylcarbodiimide, N, N′-di-2,4,6-triisopropylphenylcarbodiimide, N, N′-di-2,4 Examples thereof include 6-triisobutylphenyl carbodiimide. The monocarbodiimide compound used as the end-capping agent may be a single type or a mixture of a plurality of types, but N, N in terms of heat resistance and reactivity and affinity with aliphatic polyesters. '-Di-2,6-diisopropylphenylcarbodiimide (hereinafter referred to as TIC) is preferable. When a plurality of types of monocarbodiimide compounds are used in combination, 50% or more of the total amount of monocarbodiimide compounds used as the end-capping agent is TIC. It is preferable that

  As a method of blocking the terminal carboxyl group with the monocarbodiimide compound, it can be obtained by reacting an appropriate amount of the monocarbodiimide compound as a terminal blocking agent in the molten state of the aliphatic polyester. From the viewpoint of suppressing low molecular weight substances, it is preferable to add and react the monocarbodiimide compound after completion of the polymerization reaction of the polymer. Examples of the mixing and reaction of the above-described monocarbodiimide compound and aliphatic polyester include, for example, a method of adding a monocarbodiimide compound to a molten aliphatic polyester immediately after the completion of the polycondensation reaction, stirring and reacting, and an aliphatic polyester chip. A method of adding and mixing a monocarbodiimide compound and then kneading and reacting with a reactor or an extruder, etc., a method of continuously adding a liquid monocarbodiimide compound to aliphatic polyester with an extruder, kneading and reacting, It can be carried out by a method of kneading and reacting a blend chip obtained by mixing a concentration-containing aliphatic polyester master chip and an aliphatic polyester homochip with an extruder or the like.

  The carbodiimide compound used as a hydrolysis inhibitor in the present invention is not particularly limited, but when a polycarbodiimide compound is used, 4,4′-dicyclohexylmethane diisocyanate represented by the following chemical formula [Chemical Formula 1] And at least one of isophorone diisocyanate represented by the following chemical formula [Chemical Formula 2] and tetramethylxylylene diisocyanate represented by the following chemical formula [Chemical Formula 3], and has two or more carbodiimide groups in the molecule. And it is preferable that it is a polycarbodiimide compound by which the isocyanate terminal is sealed with carboxylic acid.

The polycarbodiimide compound is a 4,4′-dicyclohexylmethane diisocyanate (hereinafter abbreviated as HMDI) represented by the chemical formula [Chemical Formula 1], or an isophorone diisocyanate (hereinafter, represented by the chemical formula [Chemical Formula 2]). Abbreviated as IPDI), carbodiimide derived from any one of tetramethylxylylene diisocyanate (hereinafter abbreviated as TMXDI) represented by [Chemical Formula 3] of the above chemical formula, or a mixture of the above two compounds, or 3 The main component is a carbodiimide derived from any mixture of the seed mixture and having two or more carbodiimide groups, preferably 5 or more carbodiimide groups in the molecule. The upper limit of carbodiimide groups in polycarbodiimide is 20. Such a carbodiimide can be produced by a carbodiimidization reaction accompanied by a decarbonation reaction using HMDI, IPDI, or TMXDI, or a mixture of the above two compounds or a mixture of the three compounds as a raw material. Among these, a carbodiimide containing 50% by weight or more of HMDI is preferable and a carbodiimide containing 80% by weight or more of HMDI is more preferable in that the obtained fiber has excellent mechanical properties.
The polycarbodiimide compound used in the present invention is excellent in thermal stability even when an unreacted polycarbodiimide compound is present in the aliphatic polyester resin. Since generation | occurrence | production of property gas can be suppressed, it is preferable that the isocyanate terminal is what was sealed with the terminal using carboxylic acid. Among such carboxylic acids, those preferably used are monocarboxylic acids such as cyclohexanecarboxylic acid, benzoic acid, trimellitic anhydride, 2-naphthoic acid, nicotinic acid, isonicotinic acid, 2-fluoic acid, propionic acid. , Butyric acid, isobutyric acid, methacrylic acid, palmitic acid, stearic acid, oleic acid, cinnamic acid, glyceric acid, acetoacetic acid, benzylic acid, anthranilic acid, etc., among which cyclohexanecarboxylic acid is most preferred .
In order to reduce the amount of pyrolysis gas generated by thermal degradation of the unreacted polycarbodiimide compound, the amount of polycarbodiimide compound added is equal to or less than twice the total carboxyl group terminal amount of the aliphatic polyester as the carbodiimide group equivalent. It is preferable to control . The amount of the polycarbodiimide compound added is more preferably 1.5 times equivalent or less, more preferably 1.2 times equivalent or less of the total carboxyl group terminal amount.

  In the present invention, the glycidyl-modified compound having isocyanuric acid as a basic skeleton used as an endblocker for aliphatic polyesters is represented by the following chemical formula [Chemical Formula 4].

(Here, at least one of R _{1 to} R ₃ is a glycidyl ether or a glycidyl ester, and the rest are functional groups such as hydrogen, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, and an allyl group).
The glycidyl-modified compound is not particularly limited as long as it is a compound represented by the above chemical formula [Chemical Formula 4], but any one of R ₁ to _{3 in} the chemical formula [Chemical Formula 4] is a glycidyl group. Further, diallyl monoglycidyl isocyanurate in which the remaining two are allyl groups, or mono-allyl diglycidyl isocyanurate in which any two are glycidyl groups and the remaining one is an allyl group among R _{1 to} R _{3 in} the above chemical formula [Chemical Formula 4] Alternatively, tris (2,3-epoxypropyl) isocyanurate in which all of R _{1 to} R _{3 in} the above chemical formula [Chemical Formula 4] are glycidyl groups is preferably used.

  In addition, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, an antistatic agent, a hydrophilic agent, and the like are added to the aliphatic polyester as long as the effects of the present invention are not impaired. Also good.

  In the present invention, nylon 6, nylon 66, nylon 6-10, nylon 12, or a copolymer or a modified product thereof can be used alone or blended as the polyamide constituting the blended polymer with the aliphatic polyester. . In selecting such a polyamide, it is preferable to select a polyamide having a small melting point difference from the aliphatic polyester.

In addition, a crystal nucleating agent, a matting agent, a pigment, an antifungal agent, an antibacterial agent, a flame retardant, an antistatic agent, a hydrophilic agent, and the like may be added to the polyamide as long as the effects of the present invention are not impaired. .
The most preferred blend polymer in the present invention is one using the above-mentioned polylactic acid as the aliphatic polyester and nylon 6 as the polyamide. Nylon 6 has a melting point of 220 ° C. and a melting point of 170 ° C. of polylactic acid, and is particularly preferable because it has a high affinity and spinnability in the case of composite spinning. Furthermore, since the difference in melting point is small, one of the polymers is not excessively melted when heat-bonding, and this is preferable from the viewpoint that the water permeability performance required for the drain filter is not impaired.

  The weight ratio of the aliphatic polyester: polyamide blended in the present invention is preferably in the range of 50:50 to 95: 5, more preferably 55:45 to 90:10, and most preferably 60:40 to 85:15. If the weight ratio of the polyamide exceeds 50, not only will the effect of lowering the environmental impact of using aliphatic polyester blends be reduced, but the natural degradation of the filter material will not proceed sufficiently even after the ground is improved. Since the drain material may become entangled with the blade edge during the subsequent shield work, or the ground excavation work may be hindered, it is not preferable. If the weight ratio of the polyamide is less than 5, the nonwoven fabric has insufficient mechanical properties such as tensile strength, tensile elongation, and tear strength, and the filter is likely to break during construction and during the use of the drain material. This is an undesirable direction.

The thermoplastic filament made of the blend polymer in the present invention is preferably formed by finely dispersing polyamide in the cross-sectional direction at an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex. If the average single fiber fineness of the polyamide is finely dispersed within the above range, the tensile strength, tensile elongation and tear strength of the nonwoven fabric are sufficient, and the aliphatic polyester component tends to be biodegraded, which is preferable. . The average single fiber fineness of the finely dispersed polyamide is more preferably in the range of 2 × 10 ^{−7 to} 5 × 10 ⁻⁴ dtex, and more preferably in the range of 9 × 10 ⁻⁷ to 4 × 10 ⁻⁴ dtex. Most preferred.

  In addition, the average single fiber fineness of the polyamide component in this invention is calculated | required with the following method. That is, 10 small sample samples are randomly collected from a sample, embedded in an epoxy resin, cut out as an ultrathin section in a cross-sectional direction, and 40,000 to 100,000 using a transmission electron microscope (TEM, for example, Hitachi H7100FA type). Take a photo at double magnification. The average value is calculated by measuring the size of the cross-sectional area of the polyamide component from each sample by 20 pieces in total, calculating a mean value, converting this to the fiber diameter of the circular fiber, and correcting the polymer density. is there. If it is difficult to distinguish between polyamide and aliphatic polyester in TEM observation, the sample may be appropriately stained.

In the present invention, as a method for finely dispersing the polyamide in the aliphatic polyester, it is preferable to knead by a melt kneading extruder, a stationary kneader or the like. In addition, as a method for improving kneadability, the combination of polyamide and aliphatic polyester is also important, and it is preferable to optimize the compatibility of the combined polymer. As a compatibility index, the difference in solubility parameter (SP value) between polyamide and aliphatic polyester is preferably 1 to 9 (MJ / m ³ ) ^1/2 . Here, the SP value is a parameter reflecting the cohesive strength of a substance defined by (evaporation energy / molar volume) ^1/2 . For example, “Plastic Data Book” Asahi Kasei Amidus Co., Ltd./Plastics Editorial Department, 189 It is described on the page. If the difference in SP value between the polyamide and the aliphatic polyester is in the range of 1 to 9 (MJ / m ³ ) ^1/2 , the compatibility between the polymers will be improved and the dispersibility of the polyamide will be improved. This is a preferable direction because stability tends to be improved. For example, the above-mentioned combination of polylactic acid and nylon 6 has a difference in SP value of 2 (MJ / m ³ ) ^1/2 and is preferable from the viewpoint of compatibility.

  Further, it is preferable to use a polyamide having a melt viscosity lower than that of the aliphatic polyester as such a polyamide, because the polyamide is easily deformed and easily dispersed by shearing force.

  Although the said blend polymer is used as a raw material polymer of a thermoplastic filament nonwoven fabric, when manufacturing a thermoplastic filament nonwoven fabric by the spun bond method mentioned later, you may perform a blend and spinning continuously. Moreover, in this thermoplastic filament nonwoven fabric, thermoplastic filaments other than the thermoplastic filament which consists of this blend polymer may be included.

The thermoplastic filament nonwoven fabric in the present invention preferably has a water permeability of 1 × 10 ⁻¹ cm / second or more. When the water permeability coefficient is smaller than 1 × 10 ⁻¹ cm / second, the water collecting capacity of the drain material tends to be insufficient, which is not preferable. In addition, the permeability coefficient of the filter is based on the constant water level permeability test of the JIS A-1218 soil permeability test method, using a drain filter instead of the soil, and obtaining from the relationship between the drain filter thickness and the permeability. it can. In this case, the thickness of the filter used was a measurement result of a pressure load of 2 kPa according to JIS L1908.

Moreover, it is preferable that the single fiber fineness of the thermoplastic filament which consists of a blend polymer in this invention is 1-8 dtex. When the single fiber fineness of such a filament is less than 1 dtex, not only fine particles in the soil but also water permeability is hindered by the fibers, so that the water collecting performance of the drain material is lowered and the soil is effectively improved. This is not preferable because the quality tends to be lost. On the other hand, when the single fineness of the filament exceeds 8 dtex, fine particles in the soil pass through the nonwoven fabric, which is not preferable because the performance and effects required for a filter tend not to be obtained sufficiently.
In addition, the single fiber fineness referred to here is a sample of 10 small pieces taken at random from a sample, photographed 500 to 3000 times with a scanning electron microscope or the like, and 10 fibers from each sample, a total of 100 fibers. The fiber diameter calculated by rounding off the average of those values and rounding to the nearest 0.01 μm is corrected with the density of the polymer, and the first decimal place is rounded off.
Furthermore, the cross-sectional shape of the thermoplastic filament is not limited at all, and a round shape, an oval shape, a hollow round shape, a flat shape, or an irregular shape such as an X shape, a Y shape, or a multileaf shape is preferably used. However, the round shape is the most preferable because it is easy to manufacture and is less susceptible to needle damage during tufting.

The basis weight of the thermoplastic filament nonwoven fabric in the present invention is preferably ²⁰ to 200 g / m ² . When the weight per unit area is less than 20 g / m ² , even if the single fiber fineness is reduced to some extent, the inter-fiber gap increases, and fine soil particles pass through the nonwoven fabric. There is a tendency to get lost. On the other hand, if the basis weight exceeds 200 g / m ² , the water permeability is decreased, so that not only the water collecting performance of the drain material tends to be insufficient but also the cost tends to increase, which is not preferable. More preferably, the nonwoven fabric has a basis weight of 25 to 150 g / m ² , and more preferably 30 to 100 g / m ² .

  Here, the basis weight is obtained by the following method. In other words, three samples with a size of 50 cm in length x 50 cm in width are taken and each weight is measured, and the average value of the obtained values is converted per unit area and calculated by rounding off the first decimal place. It is.

  Further, in the thermoplastic filament nonwoven fabric of the present invention, the basis weight of the nonwoven fabric and the tensile strength of the nonwoven fabric, the tensile elongation of the nonwoven fabric and the tear strength of the nonwoven fabric satisfy both the following formulas (I) and (II) It is preferable that it exists in.

200 ≧ Y × Z / X ≧ 80 (I)
T / X ≧ 0.9 (II)
However, X: Fabric weight of nonwoven fabric (g / m ² ), Y: Tensile strength of nonwoven fabric (N / 5 cm), Z: Tensile elongation (%) of nonwoven fabric, T: Tear strength of nonwoven fabric (N)
In the above formula (I), a more preferable range is 195 ≧ Y × Z / X ≧ 85, and a further preferable range is 190 ≧ Y × Z / X ≧ 90. In the above formula (I), when Y × Z / X ≦ 200 is not satisfied, the strength of the nonwoven fabric is sufficient, but the texture is hard and the performance as a drain filter tends to be inferior. Moreover, in the said Formula (I), when not satisfy | filling YxZ / X> = 80, since the intensity | strength of a nonwoven fabric becomes inadequate, it is unpreferable.

  In the above formula (II), a more preferable range is T / X ≧ 0.95, and a further preferable range is T / X ≧ 1.0. If the basis weight and tear strength do not satisfy the above formula (II), the balance between the basis weight and tear strength of the nonwoven fabric will be insufficient, and the nonwoven fabric tends to be easily torn during construction or during the drainage period. Therefore, it is not preferable.

  Here, the tensile strength and tensile elongation are obtained by the following methods. That is, 10 specimens each having a width of 5 cm and a length of 30 cm are collected for each of the longitudinal direction (sheet length direction) and the lateral direction (sheet width direction) of the nonwoven fabric. The test piece is subjected to a tensile test with a constant speed extension type tensile tester at a gripping interval of 20 cm and a tensile speed of 10 ± 1 cm / min, and the strength (N) at the maximum load and the elongation at the maximum load until breaking. Are measured to the order of 0.1 N and 1 mm, respectively. The tensile strength (N) is obtained by dividing the strength of the maximum load obtained here by the width of the test piece (5 cm) and rounding off to the second decimal place. The tensile elongation (%) is obtained by dividing the elongation obtained by measurement by the test piece length (20 cm) and rounding off the second decimal place. Next, the average values of the tensile strength and tensile elongation in the machine direction and the transverse direction are calculated, and the first decimal place is rounded off. The tensile strength (N / 5 cm) of the nonwoven fabric is the greater of the tensile strength in the machine direction and the transverse direction, and the corresponding tensile elongation (%) is the tensile elongation (%) of the nonwoven fabric. And Moreover, the fabric weight of a nonwoven fabric is calculated | required with the following method. In other words, three samples with a size of 50 cm in length x 50 cm in width are taken and each weight is measured, and the average value of the obtained values is converted per unit area and calculated by rounding off the first decimal place. It is. Further, the tear strength (N) of the nonwoven fabric of the present invention is JIS L1906 (2000 version) 5.4 a) as a reference, a sample having a size of 5 cm × 25 cm by a trapezoid method, a short side of 10 cm and a long side of 15 cm. An isosceles trapezoidal mark is made, a 1 cm cut is made in the center of the short side at right angles to the short side, the grip width is 5 cm, the grip interval is 20 cm, the tensile speed is 10 cm / min, and the maximum load shown when tearing is 0.1 N Measure to the order of. The measurement is performed at 5 points each in the longitudinal direction and the transverse direction, the average value of each is calculated, the first decimal place is rounded off, and the larger one of the longitudinal direction and the lateral direction is taken as the tear strength of the nonwoven fabric.

  In the present invention, the thermoplastic filament constituting the thermoplastic filament nonwoven fabric preferably contains 0.1 to 5.0 wt% of aliphatic bisamide and / or alkyl-substituted aliphatic monoamide. By containing 0.1 wt% or more of aliphatic bisamide and / or alkyl substituted aliphatic monoamide, the frictional resistance of the filament surface is reduced, and the peelability of the nonwoven fabric from the embossing roll and / or calender roll is improved, A stable nonwoven fabric can be conveyed, which is preferable. Moreover, when the content is 5.0 wt% or less, it is preferable that the spinnability is hardly deteriorated. A more preferable content range is 0.3 to 4.0 wt%, and a further preferable range is 0.5 to 2.0 wt%. In the present invention, aliphatic bisamides or alkyl-substituted aliphatic monoamides may be used singly or in combination.

  The aliphatic bisamide used in the present invention is not particularly limited, and examples thereof include saturated fatty acid bisamides, unsaturated fatty acid bisamides, and aromatic fatty acid bisamides, such as methylene bis stearamide, ethylene bis stearamide, Examples thereof include ethylene bisvalmitic acid amide and ethylene bisoleic acid amide, and a plurality of these may be used in combination.

  Examples of the alkyl-substituted aliphatic monoamide used in the present invention include compounds having a structure in which an amide hydrogen such as a saturated fatty acid monoamide or an unsaturated fatty acid monoamide is substituted with an alkyl group, and N-lauryl lauric acid amide and N-palmityl Examples thereof include palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, and a plurality of these may be used in combination.

  In order to contain the aliphatic bisamide and / or the alkyl-substituted aliphatic monoamide in the thermoplastic filament, there are methods such as applying to the surface of the thermoplastic filament, but a method of adding to the blend polymer as a raw material is preferable. The method of adding the aliphatic bisamide and / or the alkyl-substituted aliphatic monoamide to the blend polymer as a raw material for spinning is not limited at all, but the raw resin and the substance to be added are previously heated and melt mixed. The most preferable method is to prepare a master chip and add the necessary amount to the raw material resin during spinning to adjust the amount of the added substance.

  The thermoplastic filament nonwoven fabric used as a drain filter in the present invention is a long-fiber nonwoven fabric composed of continuous filaments, and is obtained by a spunbond method from the viewpoint of high production efficiency and excellent mechanical strength and dimensional stability. Long fiber nonwoven fabric is most preferred.

  In this spunbond method, a melted raw material polymer is extruded from a nozzle, and is drawn and drawn by a high-speed suction gas to form a filament, which is charged and opened, and collected and collected on a moving conveyor to form a fiber web. In this method, the web is integrated into a sheet by mechanical entanglement, thermal bonding, binder resin bonding, or a combination of these methods.

  In the present invention, the temperature at which the raw polymer is melted is preferably 30 to 90 ° C higher than the melting point of the aliphatic polyester, more preferably 40 to 80 ° C, and most preferably 50 to 70 ° C. When the difference between the melting temperature and the melting point of the aliphatic polyester is less than 30 ° C., the melt viscosity of the raw material becomes too high, and the spinnability tends to become unstable, which is not preferable. Further, when the difference between the melting temperature and the melting point of the aliphatic polyester exceeds 90 ° C., the thermal decomposition of the aliphatic polyester tends to be particularly severe, which is not preferable.

Furthermore, the spinning speed at which the filament is drawn by suction is preferably 1500 to 6000 m / min. When the spinning speed is less than 1500 m / min, the filament strength may be insufficient due to insufficient stretching, which is not preferable. Further, when the spinning speed exceeds 6000 m / min, the spinning stability tends to deteriorate, which is not preferable. A more preferable spinning speed range is 2000 to 5000 m / min.
As a method for integrating the fiber web, mechanical entanglement, thermal bonding, binder resin bonding, or a combination of these methods is preferable. The mechanical entanglement in the present invention is preferably a needle punch process in which filaments are entangled with a needle having a protrusion, or a water jet punch process in which filaments are entangled with a columnar water flow.

In the case of such needle punching treatment, those treated at a needle density of 20 to 200 times / cm ² are preferable. When the needle density is less than 20 times / cm ² , the entanglement is insufficient and the strength tends to be low, which is not preferable. In addition, when the needle density exceeds 200 times / cm ² , the entanglement is sufficient, but the filament is severely damaged, and the strength of the nonwoven fabric tends to decrease. A more preferable needle density is 30 to 150 times / cm ² .

  In the case of the water jet punching process, the front and back surfaces are each treated once or more at a water pressure of 5 to 20 MPa, whereby the entanglement can be appropriately performed and a nonwoven fabric with sufficient strength can be provided.

Further, in the present invention, the integration by thermal bonding means that the fibers are thermally bonded to each other at the contact point, or the thermal bonding is partially bonded within a range of 5 to 50% with respect to the total area of the nonwoven fabric. Are preferred. As a method for thermally bonding the fibers to each other at the contact point, a heat treatment using a pair of flat rolls or a process of blowing hot air (air-through bonding process) is preferable. Further, as a method of partially thermally bonding, a heat embossing process using a pair of embossing rolls or a heat embossing process using an embossing roll and a flat roll is preferable. In addition, in such partial thermal bonding, when the ratio of the bonding area is less than 5% with respect to the total area of the nonwoven fabric, the strength of the nonwoven fabric tends to be insufficient, and conversely exceeds 50%. Is not preferred because the texture of the nonwoven fabric tends to be too hard. A more preferable ratio of partial thermal bonding is 8 to 30%. Furthermore, the temperature of these thermal bonding is preferably 5 to 70 ° C., more preferably 10 to 60 ° C. lower than the melting point of the aliphatic polyester constituting the filament. That is, when the temperature difference between the thermal bonding temperature and the melting point of the aliphatic polyester is less than 5 ° C., the thermal bonding tends to be too strong, and conversely, when it exceeds 70 ° C., the thermal bonding is insufficient. This is not preferable.
The drain filter thus produced is used by being bonded to a plate-like core material having parallel grooves formed in the longitudinal direction. When the drain filter is bonded to the core material, a water passage is formed between the groove shape of the core material and the filter, through which water in the ground is discharged to the ground surface. The method for bonding the core material and the drain filter is not particularly limited, and for example, means such as thermal bonding or adhesive can be used.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

  Moreover, the evaluation method used in the Example and its measurement conditions are demonstrated below.

(1) Polymer melt viscosity (poise)
The melt viscosity of the polymer was measured with a capillarograph 1B manufactured by Toyo Seiki Seisakusho. The polymer storage time from sample introduction to measurement start was 10 minutes.

(2) Melting point (° C)
Using a Perkin Elmer DSC-7, the peak top temperature indicating the melting of the polymer at 2nd run was taken as the melting point of the polymer. The temperature rising rate at this time was 20 ° C./min, and the sample amount was 10 mg.

(3) Weight average molecular weight The weight average molecular weight of polylactic acid was calculated | required with the following method. Tetrahydrofuran was mixed with the chloroform solution of the sample to obtain a measurement solution, which was measured at 25 ° C. using a gel permeation chromatograph (GPC) Waters 2690 manufactured by Waters, and the weight average molecular weight was determined in terms of polystyrene. Three measurements were performed for each sample, the average value was calculated, and the weight average molecular weight was rounded off to the nearest thousand.

(4) Single fiber fineness (decitex):
Ten small sample samples are taken at random from the nonwoven fabric, photographed at 500 to 3000 times with a scanning electron microscope or the like, 10 from each sample, the diameter of 100 fibers in total, and the average value thereof. The fiber diameter calculated by rounding off the 0.01 μm position was corrected by the polymer density, and the first decimal place was rounded off.

(5) Weight per unit area (g / m ² ):
Three samples each having a size of 50 cm in length and 50 cm in width were collected from the nonwoven fabric, and each weight was measured. The average value of the obtained values was converted per unit area, and the first decimal place was rounded off.

(6) Dispersion state of polyamide component (average single fiber fineness: decitex)
Ten small piece samples are randomly collected from the nonwoven fabric, embedded in an epoxy resin, cut in the cross-sectional direction, cut into ultrathin sections, and cut into 40,000 to 100,000 with a transmission electron microscope (TEM: H7100FA type manufactured by Hitachi). Photos were taken at double magnification. Measure the cross-sectional area of the polyamide component from each sample, 20 in total, 200 in total, calculate the average value thereof, convert this to the fiber diameter of the circular fiber, and correct it with the polymer density to obtain the polyamide component The single fiber fineness was determined. In addition, when it was difficult to distinguish between polyamide and aliphatic polyester in TEM observation, the sample was appropriately stained.

(7) Tensile strength, tensile elongation, tear strength (Tensile strength and tensile elongation)
With reference to 5.3.1 of JIS L1906 (2000 version), a tensile test of 10 points each in the longitudinal and lateral directions of the sheet under the conditions of a sample size of 5 cm × 30 cm, a gripping interval of 20 cm, and a tensile speed of 10 cm / min. Measure the tensile strength when the sample is ruptured, and measure the elongation of the sample at the maximum load to the 1 mm unit, and use this elongation rate (the length of elongation relative to the original length) as the tensile elongation. The average value in each direction and horizontal direction was calculated by rounding off the first decimal place.

  At this time, the larger one of the tensile strengths in the longitudinal direction and the transverse direction was defined as the tensile strength of the nonwoven fabric: Y, and the tensile elongation corresponding to Y was defined as Z. It was verified whether the relationship between the values of Y and Z and the basis weight X measured in the above (5) conforms to the above-mentioned formula (I).

(Tearing strength)
With reference to JIS L1906 (2000 version) 5.4 a), a trapezoidal method is used to mark an isosceles trapezoid with a short side of 10 cm and a long side of 15 cm on a sample size of 5 cm x 25 cm. A 1 cm cut was made at right angles to the side, and the maximum load when the grip was torn at a grip width of 5 cm, a grip interval of 20 cm, and a tensile speed of 10 cm / min was measured. The measurement was performed at 5 points for each of the longitudinal and lateral directions of the sheet, and the average value in the longitudinal and lateral directions was calculated by rounding off the first decimal place.

  At this time, among the tear strengths in the longitudinal direction and the transverse direction, the larger value was taken as the tear strength T of the nonwoven fabric. It was verified whether the relationship between this T and the basis weight X measured in the above (5) conforms to the above-mentioned formula (II).

(Example 1)
Melt viscosity 570 poise (240 ° C., shear rate 2432 sec ⁻¹ ), melting point 220 ° C. nylon 6 (40 wt%), weight average molecular weight 120,000, melt viscosity 300 poise (240 ° C., shear rate 2432 sec ⁻¹ ), melting point 170 ° C. Of poly (L-lactic acid) (optical purity 99.5% or more) (60 wt%) was kneaded at 240 ° C. with a twin screw extruder kneader to obtain a blend polymer chip.

Using this blend polymer chip as a raw material, the raw material is melted by an extruder at 240 ° C., spun from a round pore at a spinning temperature of 240 ° C., and then spun at a spinning speed of 2500 m / min by an ejector. The web obtained by opening the yarn with a fiber device and collected on a moving conveyor is used with an embossing roll and a flat roll having a crimping area ratio of 13%, a roll temperature of 135 ° C., and a linear pressure. Thermal bonding was performed under the condition of 50 kg / cm to obtain a nonwoven fabric having a single fiber fineness of 2.5 dtex and a basis weight of 30 g / m ² .

(Example 2)
To the blend polymer chip used in Example 1, 0.5 wt% of ethylenebisstearic acid amide was added, melted in an extruder at 240 ° C., spun from a round pore at a spinning temperature of 240 ° C., and then ejector An embossing roll that spins at a spinning speed of 2800 m / min, opens the yarn with a known opening device, and collects the web collected on the moving conveyor with a crimping area ratio of 16%. And a flat roll, and heat-bonded under the conditions of a roll temperature of 140 ° C. and a linear pressure of 40 kg / cm, to obtain a nonwoven fabric having a single fiber fineness of 2.3 dtex and a basis weight of 50 g / m ² .

(Example 3)
Under the same conditions as in Example 1, only the weight ratio of nylon 6: poly (L-lactic acid) was changed to 20:80 to obtain a blend chip. To this blend polymer chip, 0.5% by weight of ethylenebisstearic acid amide was added, the raw material was melted at 240 ° C with an extruder, spun from a round pore at a spinning temperature of 245 ° C, and then spun with an ejector. An embossing roll and a flat roll that are spun at a speed of 3900 m / min, opened the yarn with a known opening device, and collected on the moving conveyor, with a crimping area ratio of 13% Was used for heat bonding under the conditions of a roll temperature of 140 ° C. and a linear pressure of 50 kg / cm to obtain a nonwoven fabric having a single fiber fineness of 2.5 dtex and a basis weight of 90 g / m ² .

Example 4
To the blend polymer chip used in Example 1, 0.5 wt% of ethylenebisstearic acid amide was added, and further 1 wt% of TIC was added with respect to the content of poly (L-lactic acid). After melting and spinning from the round pores at a spinning temperature of 245 ° C., spinning with an ejector at a spinning speed of 2500 m / min, opening the yarn with a known opening device, and collecting on a moving conveyor The resulting web was thermally bonded using an embossing roll and a flat roll having a crimp area ratio of 16% under the conditions of a roll temperature of 135 ° C. and a linear pressure of 50 kg / cm, and a single fiber fineness of 3 dtex and a basis weight. A nonwoven fabric of 110 g / m ² was obtained.

(Example 5)
A nonwoven fabric was manufactured under the same conditions as in Example 4 except that the discharge rate and the moving speed of the net conveyor were adjusted so that the single fiber fineness was 5.0 dtex and the basis weight was 140 g / m ² .

(Comparative Example 1)
A non-woven fabric was produced under the same conditions as in Example 2 except that the polylactic acid resin described in Example 1 was melted by an extruder using a single component and the spinning temperature was 230 ° C., and the single fiber fineness was 2.3 dtex, the basis weight was 50 g / An m ² polylactic acid single-component nonwoven fabric was obtained.

(Comparative Example 2)
A non-woven fabric was produced under the same conditions as in Example 4 except that a polylactic acid resin was used as a single component and the spinning temperature was 230 ° C. as in Comparative Example 1, and the single fiber fineness was 2.8 dtex and the basis weight was 110 g / m ^2. A non-woven fabric was obtained.

Although the characteristic of the obtained long fiber nonwoven fabric is as having shown in Table 1, although all the nonwoven fabrics of Examples 1-5 contain poly (L-lactic acid) resin which is aliphatic polyester, The tensile strength, elongation, and tear strength were excellent, satisfying the above formulas (I) and (II), and excellent properties as a drain filter.
On the other hand, the nonwoven fabrics of Comparative Examples 1 and 2 were inferior in mechanical properties and did not have desirable properties as a drain filter.

Claims (7)

A drain filter comprising a thermoplastic filament nonwoven fabric, wherein the nonwoven fabric includes a thermoplastic filament comprising a blend polymer of an aliphatic polyester and a polyamide. The single filament fineness of the thermoplastic filament made of the blend polymer is 1 to 8 dtex, the basis weight of the nonwoven fabric is 20 to 200 g / m ² , and the basis weight, tensile strength, breaking elongation and tearing of the nonwoven fabric The drain filter according to claim 1, wherein the strength satisfies the following formulas (I) and (II).
200 ≧ Y × Z / X ≧ 80 (I)
T / X ≧ 0.9 (II)
However, X: Nonwoven fabric basis weight (g / m ² ), Y: Tensile strength of nonwoven fabric (N / 5 cm), Z: Tensile elongation (%) of nonwoven fabric T: Tear strength of nonwoven fabric The drainage filter according to claim 1 or 2, wherein a water permeability coefficient is 1.0 x 10 ^-1 cm / sec or more. The drain filter according to any one of claims 1 to 3, wherein the blend polymer has an aliphatic polyester: polyamide weight ratio of 50:50 to 95: 5. 5. The polyamide component is finely dispersed at an average single fiber fineness of 1 × 10 ⁻⁷ to 1 × 10 ⁻³ dtex in a cross section of the thermoplastic filament made of the blend polymer. A drain filter as described in 1. The drain filter according to any one of claims 1 to 5, wherein the aliphatic polyester is polylactic acid and the polyamide is nylon 6. The thermoplastic filaments constituting the nonwoven fabric are thermally bonded to each other, and the thermal bonding is partially performed in a range of 5 to 50% with respect to the total area of the nonwoven fabric. The drain filter according to any one of the above.