JP2015074842A - Biodegradable filament nonwoven fabric and filter for food obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable filament nonwoven fabric consisting of biodegradable filaments comprising a polylactic acid-based polymer that are almost completely degraded after use and are easily disposed, and being excellent in transparency, dimension stability and component extraction properties, and to provide a filter for food obtained by using the same.SOLUTION: The biodegradable filament nonwoven fabric comprises polylactic acid filaments that contain a polylactic acid-based polymer having a melting point of 150°C or more as a main component, have an average fiber diameter of 15-40 μm, a birefringence of 0.005-0.025 and a crystallinity of 30-50%, and has a basis weight of 10-30 g/m. The filter for food comprises the biodegradable filament nonwoven fabric.

Description

  The present invention comprises a biodegradable long fiber nonwoven fabric excellent in transparency, dimensional stability, uniformity, and component extractability, and the food used for extraction for beverages, in particular, comprising the biodegradable long fiber nonwoven fabric Related to filters.

  Conventionally, nonwoven fabrics made of resins such as polyethylene, polypropylene, polyester, and polyamide have been used as packaging materials. However, nonwoven fabrics made of these resins are not self-degradable and are extremely stable in the natural environment. For this reason, used packaging materials have been incinerated or landfilled in incinerators. However, from the viewpoint of environmental protection, the environment for used packaging materials has been increasing for the purpose of resource recycling and greenhouse gas suppression. It is desired to develop early methods for effective use and disposal that are friendly to the environment.

  In general, it is required to make the fibers dense in order to enhance the shielding function such as filterability of the nonwoven fabric, so that the inside cannot be confirmed. When extracting components such as black tea, green tea, oolong tea, etc., a tea bag method is often used as a simple method. Paper is generally used as a packaging material used for tea bags, but there are problems such as poor transparency and inability to see the contents of the packaging material and heat sealing.

Patent Document 1 below discloses a biodegradable monofilament for tea bags having a fineness of 15 to 35 dtex made of poly-L-lactic acid. However, since the fineness is large, the transparency is high, but the boiling rate of the monofilament is low. There is a problem that it is 20% or less and the dimensional stability is low.
In addition, in the following Patent Document 2, a nonwoven fabric composed of composite short fibers of two types of polylactic acid polymers having different optical purities has been proposed, but since the shrinkage at the actual processing temperature is large, Only bad and hard nonwoven fabrics can be obtained.
Furthermore, the following Patent Document 3 discloses a nonwoven fabric obtained by thermocompression bonding of a sheath component of a composite fiber by hot air processing. Not suitable for.

JP 2001-131826 A JP 2001-49533 A JP 2007-126780 A

  The present invention is intended to solve the problems of the prior art as described above, and is composed of biodegradable long fibers made of a polylactic acid polymer that is almost completely decomposed after use and can be easily disposed of. Another object of the present invention is to provide a biodegradable long-fiber non-woven fabric excellent in transparency, dimensional stability, uniformity of formation, and component extractability, and a food filter using the same.

  As a result of intensive studies to solve the above problems, the present inventors have found that the structure and fiber diameter of the nonwoven fabric comprising the polylactic acid polymer, the basis weight of the nonwoven fabric, the formation, the thermal compression area ratio, etc. The biodegradable long-fiber non-woven fabric with excellent spinnability and uniformity of the nonwoven fabric, excellent extractability of ingredients as a food filter, and good transparency and dimensional stability is obtained. As a result, the present invention has been completed.

That is, the present invention is as follows.
[1] A polylactic acid polymer having a melting point of 150 ° C. or more as a main component, an average fiber diameter of 15 to 40 μm, a birefringence of 0.005 to 0.025, and a crystallinity of 30 consisting of polylactic acid filament is 50%, biodegradable filament nonwoven fabric, wherein the basis weight is 10 to 30 g / ^{m 2.}

  [2] The polylactic acid polymer is poly L-lactic acid, poly D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, or D-lactic acid. And a polymer selected from the group consisting of a copolymer of L-lactic acid, D-lactic acid, and hydroxycarboxylic acid, or a blend of two or more of the polymers. The biodegradable long fiber nonwoven fabric according to [1].

[3] The above-mentioned [1] or [2], wherein the biodegradable long-fiber nonwoven fabric has a thermocompression bonding area ratio of 5 to 40% and an average apparent density of 0.1 to 0.5 g / cm ³ . The biodegradable long fiber nonwoven fabric described in 1.

  [4] The biodegradable long fiber nonwoven fabric according to any one of [1] to [3], wherein the biodegradable long fiber nonwoven fabric has a transparency of 60% or more.

  [5] The biodegradable long fiber nonwoven fabric according to any one of [1] to [4], wherein the biodegradable long fiber nonwoven fabric has a boiling water shrinkage of 4.0% or less.

  [6] The biodegradable long fiber nonwoven fabric according to any one of [1] to [5], wherein the biodegradable long fiber nonwoven fabric has a tensile strength of 2 to 25 N / 30 mm.

  [7] The biodegradable long fiber nonwoven fabric according to any one of [1] to [6], wherein the formation factor of the biodegradable long fiber nonwoven fabric is 0.5 to 2.0.

  [8] The biodegradable long fiber nonwoven fabric according to any one of [1] to [7], wherein at least one layer of the biodegradable long fiber nonwoven fabric contains an aliphatic polyester having a melting point of 140 ° C. or lower.

  [9] A food filter comprising the biodegradable long fiber nonwoven fabric according to any one of [1] to [8].

  The biodegradable long fiber nonwoven fabric according to the present invention has good spinnability, excellent component extractability as a food filter, and good transparency and dimensional stability.

It is the schematic which shows an example of the apparatus which controls airflows, such as a plate-shaped dispersion board. It is a graph which shows the relationship between boiling water shrinkage | contraction rate and transparency. It is a graph which shows the relationship between draft ratio and oriented crystallinity. It is a graph which shows the relationship between spinning temperature and oriented crystallinity.

Hereinafter, embodiments of the present invention will be described in detail.
Examples of the polylactic acid polymer constituting the biodegradable long-fiber nonwoven fabric according to the present invention include poly L-lactic acid, poly D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, and L-lactic acid and hydroxycarboxylic acid. Any polymer selected from the group consisting of copolymers with acids, copolymers of D-lactic acid and hydroxycarboxylic acids, and copolymers of L-lactic acid, D-lactic acid and hydroxycarboxylic acids, or Two or more types of blends of the polymers may be mentioned. In the present invention, the polylactic acid polymer has a melting point of 150 ° C. or higher. Moreover, the stereocomplex structure which has a high melting | fusing point of 200-240 degreeC can be used by melt-spinning the blend of poly L-lactic acid and poly D-lactic acid.

  Examples of the hydroxycarboxylic acid used as a component of the polylactic acid polymer include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and hydroxyoctanoic acid. Of these, glycolic acid and hydroxycaproic acid are preferred.

  The MI of the polylactic acid polymer is preferably 5 to 30 g / 10 min, more preferably 5 to 20 g / 10 min. If the MI is 5 g / 10 min or more, the melt viscosity is appropriate, and the orientation crystallization of the fiber proceeds in the spinning process, and a sufficient single yarn strength tends to be obtained. On the other hand, when the MI is 30 g / 10 min or less, the melt viscosity is appropriate, so that single yarn breakage is less likely to occur in the spinning process, and a single yarn strength is high.

As the fiber shape of the biodegradable long fiber according to the present invention, in addition to a normal round cross section, a hollow cross section, a core-sheath composite cross section, a split composite cross section, etc., any fiber cross section depending on its purpose and application The shape can be selected.
In order to use the biodegradable long-fiber nonwoven fabric according to the present invention in the shape of a bag such as a tea bag, it is preferable that the adhesive strength is high by heat sealing using a bag making machine. In order to obtain heat-sealability with good adhesive strength, that is, high heat-seal strength, by laminating a fiber containing an aliphatic polyester having a melting point of 140 ° C. or lower on at least one surface of the nonwoven fabric to provide a difference in melting point It is preferable that only the low melting point resin component is softened or melted during the heat sealing process to function as an adhesive.

  The melting point of the aliphatic polyester is preferably 10 to 80 ° C lower than the melting point of the polylactic acid polymer, and more preferably 20 to 60 ° C. Examples of the aliphatic polyester used in the present invention include polyethylene succinate, polybutylene succinate, polyethylene terephthalate adipate, polybutylene succinate adipate, polybutylene terephthalate adipate, and polycaprolactone. Further, in addition to a single component as a fiber structure, a composite fiber structure having two components such as a sheath core structure and side-by-side, for example, a composite fiber structure having a high melting point in the core and a low melting point in the sheath, specifically, a core Is preferably a high melting point resin such as a polylactic acid polymer, and a low melting point resin such as an aliphatic polyester.

  The aliphatic polyester has an MI of preferably 5 to 30 g / 10 min, more preferably 5 to 20 g / 10 min. If the MI is 5 g / 10 min or more, the melt viscosity is appropriate, and the orientation crystallization of the fiber proceeds in the spinning process, and a sufficient single yarn strength tends to be obtained. On the other hand, when the MI is 30 g / 10 min or less, the melt viscosity is appropriate, so that single yarn breakage is less likely to occur in the spinning process, and a single yarn strength is high.

  The method of laminating low-melting fibers is, for example, a curtain spray method in which the resin is melted and a semi-molten resin or its fibrous material is applied to the nonwoven fabric, and the molten resin is discharged from a nozzle and applied to the nonwoven fabric. Examples thereof include a coating method or a method of laminating a high-melting fiber web and a low-melting fiber web and then joining them with a hot roll to obtain a laminated nonwoven fabric.

  The biodegradable long fiber nonwoven fabric according to the present invention is preferably capable of ultrasonic fusing or heat sealing. The seal strength is preferably 2N / 30 mm or more, more preferably 3N / 30 mm or more. The heat sealing conditions can be appropriately selected. For example, the heat sealing temperature conditions are preferably 5 to 80 ° C. lower than the melting point of the resin on the sealing surface.

  Furthermore, the biodegradable long-fiber nonwoven fabric according to the present invention has various other commonly used additive components, for example, impact modifiers such as various elastomers, crystal nucleating agents, and coloring prevention, as long as the desired effects are not impaired. Additives such as additives, antioxidants, heat stabilizers, plasticizers, lubricants, weathering agents, antibacterial agents, colorants, pigments, dyes and the like can be added.

  The biodegradable long fiber nonwoven fabric according to the present invention can be efficiently produced by a spunbond method. That is, the polylactic acid-based polymer is heated and melted and discharged from a spinneret, and the obtained spun yarn is cooled using a known cooling device, and is pulled and thinned by a suction device such as an air soccer. . Subsequently, the yarn group discharged from the suction device is opened and then deposited on a conveyor to form a web. Next, the web formed on the conveyor is partially subjected to thermocompression bonding using a partial thermocompression bonding apparatus such as a heated embossing roll to obtain a long fiber spunbond nonwoven fabric.

  When using the spunbond method, although not particularly limited, in order to improve the uniformity of the web, for example, a method of charging fibers with a corona facility or the like as disclosed in JP-A-11-131355, a flat plate The fiber is opened after the fibers are opened by adjusting the velocity distribution of the air flow at the ejecting part of the ejector using a device (see FIG. 1) for controlling the air flow such as a cylindrical dispersion plate. It becomes a more preferable manufacturing method by using the method of laminating | stacking on a collection surface, suppressing scattering of.

  The non-woven fabric obtained by the spunbond method has high fabric strength and has physical properties such as no short fibers falling off due to breakage of the bonding part, and because of low cost and high productivity, It is used in a wide range of applications, mainly in hygiene, civil engineering, architecture, agriculture / horticulture, and living materials.

  The fiber diameter of the biodegradable long fiber according to the present invention is 15 to 40 μm, more preferably 18 to 35 μm. If the fiber diameter is 15 μm or more, the transparency can be designed to be sufficient. In addition, if the fiber diameter is 40 μm or less because the fiber cannot sufficiently withstand the tension of the ejector during spinning and the fiber is less likely to be cut, it is made into a non-woven fabric and has mechanical strength, rigidity, and component extractability. , A filter for foods having excellent transparency and sealing properties.

  The thermocompression bonding of the biodegradable long-fiber nonwoven fabric according to the present invention is not particularly limited as long as it is a method of heat-bonding the yarns of the nonwoven fabric with heat, but a pair of heating composed of an embossing roll and a flat roll having an uneven surface structure It can be suitably performed by passing the nonwoven fabric between the rolls and forming a thermocompression bonding portion that is evenly dispersed throughout the nonwoven fabric. When thermocompression bonding is performed with an embossing roll, it is preferable that thermocompression bonding is performed at a thermocompression area ratio in the range of 5 to 40% with respect to the total area of the nonwoven fabric, more preferably 7 to 30%, and even more preferably. 7 to 20%. If the area ratio of thermocompression bonding is within this range, it is possible to perform a good thermocompression-bonding process between fibers, and to achieve appropriate mechanical strength, rigidity, transparency, component extractability, and dimensional stability of the obtained nonwoven fabric. Preferred above. The thermocompression treatment temperature and pressure should be appropriately selected depending on conditions such as the basis weight and speed of the web to be supplied, and are not generally determined, but are 10 to 90 ° C. higher than the melting point of the polylactic acid polymer. The temperature is preferably low, and more preferably 20 to 60 ° C.

  The boiling water shrinkage of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 4.0% or less, and more preferably 3.5% or less. When the boiling water shrinkage is 4.0% or less, there is almost no shrinkage due to thermoforming, etc., and the process stability is excellent, and the form retainability is excellent even in a usage form exposed to a high temperature environment close to 100 ° C. .

  The transparency of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 60% or more, more preferably 65% or more, and further preferably 70% or more. If the transparency is less than 60%, it is difficult to see the state of the contents through the nonwoven fabric, and the transparency becomes unclear.

The basis weight of the biodegradable long fiber nonwoven fabric according to the present invention is 10 to 30 g / m ² , preferably 12 to 25 g / m ² . If the basis weight is 10 g / m ² or more, sufficient mechanical strength can be secured while maintaining transparency and component extractability. On the other hand, if the basis weight is 30 g / m ² or less, transparency and component extractability can be obtained. The thickness of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 0.02 to 0.50 mm, more preferably 0.03 to 0.30 mm. When the basis weight and thickness are within this range, excellent transparency, mechanical strength, and component extractability can be obtained when used as a food filter.

The average apparent density of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 0.10 to 0.50 g / cm ³ , more preferably 0.10 to 0.30 g / cm ³ . The average apparent density is related to the rigidity, transparency, powder leakage, and component extractability of the nonwoven fabric, and if it is in the above range, the fiber gap is appropriate, so it is suitable as a food filter. If the average apparent density is 0.10 g / cm ³ or more, the mechanical strength can be sufficiently achieved while adjusting the fiber gap and appropriately suppressing the amount of powder leakage. On the other hand, if the average apparent density is 0.50 g / cm ³ or less, the fiber gap is not made too small, the component extractability is kept moderate, and the product quality can be made sufficiently high.

  The tensile strength in the MD direction of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 2 to 25 N / 30 mm, and more preferably 3 to 25 N / 30 mm. When the tensile strength is above this range, it is excellent in production stability at the time of bag making and in preventing tearing when used as a food filter.

  The formation coefficient of the biodegradable long fiber nonwoven fabric according to the present invention is preferably 0.5 to 2.0, more preferably 0.5 to 1.5. The formation coefficient is related to strength, rigidity, transparency, powder leakage and component extractability in order to indicate the uniformity of the nonwoven fabric. Since the uniformity of the nonwoven fabric is optimal within the above range, the strength, rigidity, transparency, suitability for processing into a bag shape and powder leakage are excellent as a food filter.

  The spinning temperature for obtaining the biodegradable long fiber according to the present invention is preferably a temperature that is 10 to 70 ° C. higher than the melting point of the polylactic acid polymer, and more preferably a temperature that is 10 to 50 ° C. higher. When the spinning temperature is within this range, there is no occurrence of single yarn breakage and the like, and a nonwoven fabric having an appropriate orientation crystallinity and excellent mechanical strength and dimensional stability can be obtained.

  The spinning speed when obtaining the biodegradable long fiber according to the present invention is preferably 3000 to 6000 m / min, more preferably 3500 to 5000 m / min. If the pulling speed when pulling the spun yarn is within the above range, a non-woven fabric excellent in mechanical properties and dimensional stability can be obtained with sufficient orientational crystallization of the biodegradable long fibers, and There is little possibility of yarn breakage during spinning, which is preferable from the viewpoint of the productivity of the nonwoven fabric.

  The draft ratio for obtaining the biodegradable long fiber according to the present invention is preferably 400 to 2500, and more preferably 700 to 2250. If the draft ratio when pulling the spun yarn is within the above range, a nonwoven fabric excellent in mechanical properties and dimensional stability can be obtained with sufficient orientational crystallization of the biodegradable long fibers, and Further, since there is a low possibility of occurrence of yarn breakage or roll removal during thermocompression bonding during spinning, it is also preferable from the viewpoint of the productivity of the nonwoven fabric.

  The birefringence Δn of the biodegradable long fiber according to the present invention is 0.005 to 0.025, preferably 0.010 to 0.020. When the birefringence is within this range, a nonwoven fabric having an appropriate fiber orientation and excellent mechanical strength and dimensional stability can be obtained.

  The crystallinity of the biodegradable long fiber according to the present invention is 30 to 50%, preferably 35 to 45%. When the crystallinity is within this range, a fiber excellent in mechanical strength and dimensional stability can be obtained.

  In FIG. 2, the relationship between the boiling-water shrinkage | contraction rate and transparency of the biodegradable long fiber nonwoven fabric in the Example of this invention is shown. When the fiber diameter is increased, the transparency can be increased, but since the orientation crystallization is difficult to proceed, the boiling water shrinkage ratio is increased and the dimensional stability is decreased. 3 and 4 show the relationship between the draft ratio and spinning temperature, and the oriented crystallinity indicated by the birefringence index (Δn) and the degree of crystallinity, respectively, of the biodegradable long-fiber nonwoven fabric in the examples of the present invention. As the draft ratio is increased, the oriented crystallinity of the fiber is increased. Also, under the spinning conditions of large diameters, the lower the spinning temperature, the higher the cooling efficiency and the higher the drawing efficiency and the more the oriented crystallization of the fibers can proceed. From these data, as a result of earnest research to achieve the desired effect of the present invention, the inventors of the present application have increased the oriented crystallinity while maintaining a large fiber diameter by lowering the spinning temperature and increasing the draft ratio. Achieved both improvement of transparency and shrinkage of boiling water. That is, in the non-woven fabric, the improvement in transparency and the improvement in dimensional stability expressed by the boiling water shrinkage ratio are in a contradictory relationship, but the present inventors set the fiber fine diameter and the oriented crystallinity in the optimum range. As a result, both the improvement of transparency and the improvement of dimensional stability were achieved.

  The biodegradable long fiber nonwoven fabric according to the present invention is preferably excellent in hydrophilicity so as to sink quickly without being floated on the surface when placed in hot water. As the hydrophilic agent, surfactants used for foods, for example, aqueous solutions such as sorbitan fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, ethyl alcohol solution, or a mixed solution of ethyl alcohol and water are preferable. As a method for applying, a known method such as a gravure roll method, a kiss roll method, a dipping method, or a spray method can be applied.

The biodegradable long fiber nonwoven fabric according to the present invention may be subjected to conventional post-processing, for example, deodorant, antibacterial agent, etc., within a range not impairing the desired effect of the present invention, dyeing, You may give water-repellent processing, water-permeable processing, etc.
The biodegradable long-fiber non-woven fabric according to the present invention is excellent in transparency because of its excellent transparency, so it has excellent design, and because of its excellent dimensional stability, it is a food such as green tea, black tea, coffee, etc. It has very suitable characteristics as a filter. As a food filter, a flat bag may be used, but a three-dimensional shape is preferable because the contents look better and extraction is performed effectively. As the three-dimensional shape, a tetrahedral shape, a triangular pyramid shape, and the like are preferable.

  Three-dimensional food filters are packed and sold after filling with the extractables, but they can be quickly returned to the original three-dimensional shape when the purchased consumer removes them from the bag and uses them. Required. The biodegradable long fiber nonwoven fabric of the present invention is stiff and has an appropriate rigidity, so that it can sufficiently satisfy the above requirements.

  Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to these examples. Measurement methods, evaluation methods, etc. are as follows.

(1) Average fiber diameter (μm): Using a microscope microscope (VH-8000) manufactured by Keyence Corporation, the diameter of the fiber was enlarged 1000 times and measured, and the average value of 20 fibers was obtained.

(2) Birefringence (Δn): The birefringence of the fiber immediately after towing was determined from the retardation and fiber diameter by a normal interference fringe method using a BH2 polarizing microscope compensator manufactured by OLYMPUS.

(3) Crystallinity (%): Using a differential scanning calorimeter DSC6000 manufactured by PerkinElmer Co., Ltd., with a temperature increase rate of 10 ° C./min and a temperature increase from 40 ° C. to 300 ° C., crystallization exotherm ΔHc, crystal melting The amount of heat ΔHm was measured. Crystallinity (%) was determined by the following formula:
Crystallinity χc (%) = (ΔHm−ΔHc) / 93 × 100
* 93 J / g is the heat of fusion of complete crystals of polylactic acid.

(4) Weight per unit area (g / m ² ): Measured according to JIS L-1906.

(5) Thickness (mm): The thickness at a load of 100 g / cm ² was measured by the method specified in JIS L-1906.

(6) Average apparent density (g / cm ³ ): The mass per unit volume was determined from the basis weight and thickness measured by the method defined in JIS L-1906:
Average apparent density (g / cm ³ ) = (weight per unit area g / m ² ) / ((thickness mm) × 1000)

(7) Thermocompression area ratio (%): A 1 cm square test piece was sampled and photographed with an electron microscope, the area of the thermocompression bonding part was measured from each photograph, and the average value was the area of the thermocompression bonding part. It was. Moreover, the pitch of the pattern of the thermocompression bonding part was measured in MD direction and CD direction, and the ratio of the thermocompression bonding area per unit area of the nonwoven fabric was calculated as the thermocompression bonding area ratio based on these values.

(8) Transparency (%): The reflectance (L value) was measured with a Macbeth spectrophotometer (CE-7000A type: manufactured by Sakata Ink), and the L value (L _w0 ) of the standard white board and the L value of the standard blackboard ( L _b0) as a reference to obtain the difference, the sample was determined transparency L value placed on white plate (L _w) as well as a blackboard shaped to place the L value from (L _b) according to the following formula:
Transparency (%) = {(L _w −L _b ) / (L _w0 −L _b0 )} × 100

(9) Boiling water shrinkage rate (%): In accordance with JIS L-1906, three 25 cm long x 25 cm wide test specimens were taken per 1 m width of the sample, immersed in boiling water for 3 minutes, and after natural drying, MD direction The shrinkage in the CD direction was determined. Each average value was calculated, and the larger shrinkage rate in the MD direction or the CD direction was taken as the boiling water shrinkage rate of the nonwoven fabric.

(10) Tensile strength (N / 30 mm): Using an autograph AGS-5G manufactured by Shimadzu Corporation, a 30 mm wide sample was stretched at a grip length of 100 mm and a tensile speed of 300 mm / min, and the resulting load at break Was measured 5 times in the MD direction of the nonwoven fabric, and the average value was obtained.

(11) Formation coefficient: A test piece of 20 cm × 30 cm was collected, and a transmission image obtained by photographing a range of 18 cm × 25 cm with a CCD camera using a Nomura Corporation formation tester (FMT-MIII) measuring device was 128 × 128. The intensity of light received by each pixel was measured, and the transmittance was calculated. The formation coefficient is a value obtained by dividing the standard deviation (σ) of the transmittance of each minute part (5 mm × 5 mm) of the measurement sample by the average transmittance (E). The higher the uniformity is.
Formation coefficient = σ / E × 100

(12) Heat seal strength (N / 30 mm): Using a Autograph AGS-5G model manufactured by Shimadzu Corporation, the heat seal portion of a 30 mm width sample is peeled off and attached approximately 50 mm in the vertical direction, grasping length 50 mm, tensile speed Elongation was performed at 100 mm / min, and the resulting load at break was regarded as strength. The nonwoven fabric was measured five times in the MD direction, and the average value was obtained. The heat seal conditions were a seal temperature of 150 ° C., a seal time of 1 second, a pressure of 0.5 MPa, and a seal area of 7 mm × 25 mm.

(13) Draft ratio: The draft ratio was calculated from the following formula:
Draft ratio = spinning speed (m / min) / discharge linear velocity (m / min)
Discharge linear velocity (m / min) = single hole discharge amount (g / min) / {melt density (g / cm ³ ) × [nozzle diameter (cm) / 2] ² × π}
* Polylactic acid melt density: 1.11 g / cm ³ used

(14) MI (g / 10 min): Melt indexer (manufactured by Toyo Seiki Co., Ltd .: MELT INDEXER S-101) melt flow rate apparatus, orifice diameter 2.095 mm, orifice length 0.8 mm according to JIS K-7210, It calculated | required by calculating the discharge amount (g) of the molten polymer per 10 minutes from the time required to discharge a fixed volume on condition of a load of 2.16 kg and measurement temperature of 190 degreeC.

[Example 1]
A polylactic acid polymer having a melting point of 167 ° C. and an MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus, melted at 205 ° C. A polylactic acid long fiber having an average fiber diameter of 20 μm was obtained by melt spinning at a ratio of 2240. Next, this fiber is spread and dispersed by using a dispersing device (an inclination angle of 4 ° with respect to the flat filament) to control a flat air flow to produce a web having a basis weight of 12 g / m ² , and between the embossing roll and the flat roll. Was subjected to partial thermocompression bonding at a thermocompression area ratio of 15% to obtain a biodegradable long fiber nonwoven fabric. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 2]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the polylactic acid long fiber was spun so that the average fiber diameter was 26 μm in Example 1. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 3]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the polylactic acid long fiber was spun so as to have an average fiber diameter of 30 μm in Example 1. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 4]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 3 except that the polylactic acid long fiber nonwoven fabric was spun so as to have a basis weight of 20 g / m ^{2 in} Example 3. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 5]
Biodegradation was performed in the same manner as in Example 1 except that melt spinning was performed at a spinning speed of 4000 m / min and a draft ratio of 730 in Example 1, and the polylactic acid long fibers were spun so that the average fiber diameter was 35 μm. Long-fiber nonwoven fabric was obtained. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 6]
A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 2 except that spinning was performed so that the basis weight of the long-fiber nonwoven fabric was 20 g / m ² and thermocompression bonding was performed using a flat roll. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 7]
A polylactic acid polymer having a melting point of 167 ° C. and an MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus, melted at 205 ° C. A polylactic acid long fiber having an average fiber diameter of 30 μm was obtained by melt spinning at a ratio of 995. Next, the fiber is spread and dispersed by using a dispersing device (an inclination angle of 4 ° with respect to the flat filament) to control a flat air flow to produce a web having a basis weight of 20 g / m ² , and between the embossing roll and the flat roll. The biodegradable long-fiber nonwoven fabric was obtained by partial thermocompression bonding at a thermocompression bonding area ratio of 3%. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 8]
A polylactic acid polymer having a melting point of 167 ° C. and MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus and melted at 205 ° C., and a spinning speed of 4500 m / min from a spinneret having a spinning hole having a circular cross section is obtained. A polylactic acid long fiber having an average fiber diameter of 30 μm was obtained by melt spinning at a ratio of 995. Next, this fiber is spread and dispersed to prepare a web having a basis weight of 12 g / m ² , and a biodegradable long fiber nonwoven fabric is obtained by partial thermocompression bonding between an embossing roll and a flat roll at a thermocompression area ratio of 15%. It was. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 9]
A polylactic acid polymer having a melting point of 167 ° C. and an MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus, melted at 205 ° C. A polylactic acid long fiber having an average fiber diameter of 30 μm, melt-spun at a ratio of 995, is spread and dispersed by using a dispersing device (inclination angle of 4 ° with respect to the filament of the flat plate) to control the basis weight of 12 g / m. ^Two webs were made. Next, polybutylene succinate having a melting point of 115 ° C. and MI of 13 g / 10 min is supplied to a conventional melt spinning apparatus and melted at 205 ° C. , Using a dispersion device (inclination angle of 4 ° with respect to the filament of the flat plate) to spread and weight the biodegradable polyester long fiber having an average fiber of 15 μm melt-spun at a draft ratio of 480, and a basis weight A 3 g / m ² web was made. A biodegradable long-fiber nonwoven fabric was obtained by partial thermocompression bonding of the two-layer web between an embossing roll and a flat roll at a thermocompression area ratio of 15%. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 10]
A polylactic acid polymer having a melting point of 167 ° C. and MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus and melted at 205 ° C., and a spinning speed of 4500 m / min from a spinneret having a spinning hole having a circular cross section is obtained. A polyester long fiber having an average fiber diameter of 30 μm, melt-spun at a ratio of 995, is spread and dispersed using a dispersing device (an inclination angle of 4 ° with respect to the filament of the flat plate) using a flat plate-like air flow, and the basis weight is 10 g / m ^2. The web was made. Next, a polylactic acid polymer having a melting point of 167 ° C. and MI of 12 g / 10 min is used as a core, and a polybutylene succinate having a melting point of 115 ° C. and MI of 13 g / 10 min is used as a sheath. A flat airflow is controlled for biodegradable long fibers having an average fiber diameter of 20 μm by melting and spinning at a spinning speed of 4500 m / min and a draft ratio of 950 from a spinneret having a circular cross-section spinning hole melted at ℃ Using a dispersing device (an inclination angle of 4 ° with respect to the filament of a flat plate), the fiber was spread and dispersed to produce a web having a basis weight of 8 g / m ² . A biodegradable long-fiber nonwoven fabric was obtained by partial thermocompression bonding of the two-layer web between an embossing roll and a flat roll at a thermocompression area ratio of 15%. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Comparative Example 1]
The same as in Example 1 except that the polylactic acid long fiber melt-spun at a draft ratio of 560 in Example 1 was spun so that the average fiber diameter was 12 μm and the basis weight of the biodegradable long fiber was 20 g / m ^2. Thus, a biodegradable long fiber nonwoven fabric was obtained, but the transparency of the nonwoven fabric was low, and sufficient transparency as a food filter could not be obtained. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Comparative Example 2]
A polylactic acid polymer having a melting point of 167 ° C. and MI of 12 g / 10 min is supplied to a conventional melt spinning apparatus and melted at 230 ° C., and a spinning speed of 4500 m / min from a spinneret having a spinning hole having a circular cross section is obtained. A polylactic acid long fiber having an average fiber diameter of 30 μm was obtained by melt spinning at a ratio of 200. Next, the fiber is spread and dispersed by using a dispersing device (an inclination angle of 4 ° with respect to the flat filament) to control a flat air flow to produce a web having a basis weight of 20 g / m ² , and between the embossing roll and the flat roll. In Example 2, a biodegradable long-fiber nonwoven fabric was obtained by partial thermocompression bonding at a thermocompression area ratio of 15%, but sufficient dimensional stability as a food filter could not be obtained. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Comparative Example 3]
In Comparative Example 2, the polylactic acid long fiber melt-spun at a draft ratio of 360 was spun so that the average fiber diameter was 50 μm and the basis weight of the biodegradable long fiber was 20 g / m ² . A biodegradable long-fiber nonwoven fabric could not be obtained.

[Comparative Example 4]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 3 except that the web was prepared so that the basis weight of the polylactic acid long fiber was 40 g / m ^{2 in} Example 3. It was low and sufficient transparency as a food filter could not be obtained. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

  Since the biodegradable long fiber nonwoven fabric of the present invention is excellent in transparency, dimensional stability, and component extractability, it is suitably used as a food filter.

Claims (9)

The main component is a polylactic acid polymer having a melting point of 150 ° C. or higher, the average fiber diameter is 15 to 40 μm, the birefringence is 0.005 to 0.025, and the crystallinity is 30 to 50%. A biodegradable long-fiber non-woven fabric comprising a polylactic acid long fiber having a basis weight of 10 to 30 g / m ² .   The polylactic acid polymer is poly L-lactic acid, poly D-lactic acid, a copolymer of L-lactic acid and D-lactic acid, a copolymer of L-lactic acid and hydroxycarboxylic acid, D-lactic acid and hydroxycarboxylic acid, 2. A polymer selected from the group consisting of a copolymer with an acid and a copolymer of L-lactic acid, D-lactic acid and hydroxycarboxylic acid, or a blend of two or more of the polymers. The biodegradable long fiber nonwoven fabric described in 1. The biodegradability according to claim 1 or 2, wherein the biodegradable long-fiber nonwoven fabric has a thermocompression bonding area ratio of 5 to 40% and an average apparent density of 0.1 to 0.5 g / cm ³ . Long fiber nonwoven fabric.   The biodegradable long fiber nonwoven fabric according to any one of claims 1 to 3, wherein the biodegradable long fiber nonwoven fabric has a transparency of 60% or more.   The biodegradable long fiber nonwoven fabric according to any one of claims 1 to 4, wherein the biodegradable long fiber nonwoven fabric has a boiling water shrinkage of 4.0% or less.   The biodegradable long fiber nonwoven fabric according to any one of claims 1 to 5, wherein the biodegradable long fiber nonwoven fabric has a tensile strength of 2 to 25 N / 30 mm.   The biodegradable long fiber nonwoven fabric according to any one of claims 1 to 6, wherein the formation coefficient of the biodegradable long fiber nonwoven fabric is 0.5 to 2.0.   The biodegradable long fiber nonwoven fabric according to any one of claims 1 to 7, wherein at least one layer of the biodegradable long fiber nonwoven fabric contains an aliphatic polyester having a melting point of 140 ° C or lower.   A food filter comprising the biodegradable long fiber nonwoven fabric according to any one of claims 1 to 8.

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