JP5486332B2 - Biodegradable non-woven fabric - Google Patents

Description

  The present invention is composed of biodegradable long fibers containing as a main component a polylactic acid polymer that is almost completely decomposed after use and easy to dispose of, and has high mechanical strength, heat sealability, The present invention relates to a biodegradable long fiber nonwoven fabric excellent in dimensional stability, powder leakage and transparency.

Currently, non-woven fabrics made of resins such as polyethylene, polypropylene, polyester, and polyamide are used as packaging materials, but non-woven 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 addition, paper is often used as a packaging material used for tea bags, etc., but paper has poor transparency, the contents of the packaging material cannot be seen, and heat sealing cannot be performed. There is also.

  Many studies have been conducted on polymer blends of thermoplastic resins in order to improve the performance and diversification of known polymer materials, but in general, simply blending incompatible polymers together will result in uniform dispersion It has been difficult to achieve stable production.

  The following Patent Document 1 discloses a filter bag for beverages using a biodegradable nonwoven fabric in which short fibers are thermally welded, but a paper filter bag is excellent in heat sealability, extractability, etc., There are problems such as occurrence of fine particles, powder leakage of powder, etc., and easy removal of fibers.

  The following Patent Document 2 proposes a nonwoven fabric composed of composite short fibers of two types of polylactic acid polymers having different optical purities, but the shrinkage at the actual processing temperature is large, so the formation is poor. Only a coarse and hard nonwoven fabric can be obtained.

  Patent Document 3 below discloses a nonwoven fabric obtained by thermocompression bonding a sheath component of a composite fiber by hot air processing. However, it is bulky due to its bulkiness and large heat shrinkability, and is used for filter applications. Not suitable.

  In the following Patent Document 4, a method for producing a fiber such as a sheath core type after melting two component polymers separately using two extruders in order to improve the low thermocompression bonding property of polylactic acid is disclosed. ing. In this method, since a high melting point polymer is used for the core and a low melting point polymer is used for the sheath, the sheath is shrunk during thermocompression bonding with the roll, so that it is easy to be taken by the roll and the heat resistance is low. There is. Furthermore, there is a problem that the method becomes complicated in terms of cost and manufacturing, such as an increase in equipment.

JP 2002-177148 A JP 2001-49533 A JP 2007-126780 A JP 2007-119928 A

  The problem to be solved by the present invention is that incompatible polymer blends do not use a compatibilizing agent, can be spun without requiring large equipment, and have improved the low thermocompression characteristic unique to polylactic acid and have high mechanical properties. Biodegradable long-fiber nonwoven fabric that has strength and heat-sealability, is difficult to cause powder leakage even in fine particulate matter as a food filter, and has excellent dimensional stability and transparency, and for foods containing the same Is to provide a filter.

  The inventors of the present invention have made extensive studies to solve the above-mentioned problems and, as a result of repeated experiments, have made compatibility by selecting an aliphatic polyester copolymer having specific physical properties in blend spinning of a polylactic acid polymer. It is possible to improve the thermal stability and dispersibility without using an agent, the structure and diameter of the fibers constituting the long fibers, the blend ratio and melt flow ratio of the aliphatic polyester copolymer, the heat of the nonwoven fabric Detailed examination is performed from the viewpoint of the crimping area ratio and the shape of the thermocompression bonding part, and the spinnability of the biodegradable long fiber which is a constituent fiber is good. The present inventors have found that a biodegradable long-fiber nonwoven fabric excellent in dimensional stability and hardly fluffing and having excellent powder leakage, mechanical strength, and heat sealability can be obtained, and the present invention has been completed.

That is, the present invention is as follows.
[1] A polylactic acid polymer obtained by adding 0.5 to 10 wt% of an aliphatic polyester copolymer having a melting point of 140 ° C. or lower to 100 wt% of a polylactic acid polymer having a melting point of 150 ° C. or higher. And the aliphatic polyester copolymer is obtained by melt spinning in the range of a melt flow ratio of 0.2 to 1.5, and the polylactic acid polymer forms a sea part, and the aliphatic polyester copolymer Is obtained by integrating the sea-island type composite continuous fibers forming the island part by thermocompression bonding with a thermocompression area ratio of 5 to 40%, with a birefringence exceeding 0.012 and a boiling water shrinkage of 5% or less. A biodegradable long-fiber nonwoven fabric characterized by having a heat seal strength of 1.5 N / 25 mm or more and transparency of 50% or more.

  [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 more than the kind of the polymer, The biodegradable long fiber nonwoven fabric according to [1].

  [3] The biodegradable continuous fiber nonwoven fabric according to [1] or [2], wherein the aliphatic polyester copolymer is polybutylene succinate.

[4] Ri Der powder leakage ratio of 10% or less of the biodegradable filament nonwoven fabric, One or is fluff grade 2.5 grade or higher, according to any one of [1] to [3] Biodegradable long fiber nonwoven fabric.

[5] basis weight of the biodegradable long-fiber nonwoven fabric is 10 to 50 g / m ^2, and thickness of 0.02～0.50Mm, according to any one of [1] to [4] Biodegradable long fiber nonwoven fabric.

[6] The tensile strength when converted to the MD direction of 100 g / ^{m 2} basis weight of said biodegradable filament nonwoven fabric is 200 N / 50 mm or more, biodegradation according to any one of [1] to [5] Long fiber nonwoven fabric.

[ 7 ] The long fiber is pulled and spun at a spinning speed of 3000 to 8000 m / min, has a fineness of 1.0 to 4.0 dtex, and a crystallinity of 30 to 60%. ] The biodegradable long-fiber nonwoven fabric according to any one of [ 6 ] to [ 6 ].

[ 8 ] A food filter comprising the biodegradable continuous fiber nonwoven fabric according to any one of [1] to [ 7 ].

  The biodegradable long-fiber nonwoven fabric of the present invention is composed of sea-island type composite fibers obtained by blending a polylactic acid-based polymer with a low melting point / low crystalline aliphatic polyester copolymer. By containing a low crystalline component, the fibers can be thermocompression bonded well, and the adhesion between the fibers becomes stronger, resulting in high rigidity, excellent mechanical strength and heat seal strength, and less fuzz. Second, because the aliphatic polyester copolymer is discontinuously exposed on the fiber surface, “rolling” is less likely to occur during thermocompression bonding, and excellent in dimensional stability. Third, after use Can reduce the burden on the environment by having biodegradability. Therefore, the biodegradable long fiber nonwoven fabric of the present invention can be suitably used as a food filter.

Hereinafter, the present invention will be described in detail.
Examples of the polylactic acid polymer used in the present invention include 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- Any polymer selected from the group consisting of a copolymer of lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid, D-lactic acid and hydroxycarboxylic acid, or a blend of two or more of the polymers Is mentioned. As the polylactic acid polymer, a polymer having a melting point of 150 ° C. or higher can be suitably used.

  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 MFR of the polylactic acid polymer is preferably 20 to 120 g / 10 min, more preferably 30 to 70 g / 10 min. If the MFR is 20 g / 10 min or more, the melt viscosity is appropriate, and the fibers tend to be thinned during the spinning process, so that orientation crystallization proceeds and sufficient single yarn strength tends to be obtained. On the other hand, when the MFR is 120 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.

  Examples of the aliphatic polyester copolymer include polyethylene succinate, polybutylene succinate, polyethylene terephthalate adipate, polybutylene succinate adipate, polybutylene terephthalate adipate, polycaprolactone, and the like. Among these, polybutylene succinate is particularly preferable.

  The MFR of the aliphatic polyester copolymer is preferably 100 g / 10 min or less, more preferably 20 to 80 g / 10 min, still more preferably 30 to 70 g / 10 min. Moreover, the melt flow rate ratio of the polylactic acid polymer and the aliphatic polyester copolymer is 0.2 to 1.5, preferably 0.3 to 1.4. That is, 0.2 ≦ [melting flow rate of aliphatic polyester copolymer / melting flow rate of polylactic acid polymer] ≦ 1.5. When the melt flow rate ratio is within this range, the spinnability of the sea-island type composite fiber is good and the dispersibility of the aliphatic polyester copolymer in the fiber is good, so that stable thermocompression can be obtained. And a nonwoven fabric excellent in heat sealability and mechanical strength can be obtained.

  The sea-island structure referred to in the present invention means that a polylactic acid-based polymer forms a sea part, an aliphatic polyester copolymer forms an island part, and the island part is finely dispersed in a perfect circle, an ellipse, etc. in the cross section of the polymer blend fiber. In general, it is estimated that small islands are dispersively discontinuously dispersed in the fiber axis direction. Preferably, many islands are finer on the fiber outer circumference side than on the inner side in the fiber cross section. A structure that is dispersed and partly exposed on the fiber surface. It is presumed that the aliphatic polyester copolymer in the island portion inhibits the stretching and orientation crystallization of the polylactic acid-based polymer forming the sea portion when these blend resins are stretched. Therefore, the polylactic acid polymer ends drawing with low crystallinity, and a fiber with improved thermal adhesion can be obtained.

  In the present invention, the addition rate of the aliphatic polyester copolymer with respect to the polylactic acid-based polymer is 0.5 to 10.0 wt% from the viewpoint of improving the mechanical strength of the nonwoven fabric by improving spinnability and thermocompression bonding, Preferably it is 1.0-5.0 wt%. If the addition rate is less than 0.5 wt%, the thermocompression bonding improvement effect cannot be obtained, and the desired high-rigidity and high-strength nonwoven fabric cannot be obtained, while the addition rate exceeds 10.0 wt%. Many yarn breaks occur during spinning, a stable continuous fiber cannot be obtained, and productivity is lowered.

  The polylactic acid-based polymer used in the present invention includes other commonly used additives such as impact modifiers such as various elastomers, crystal nucleating agents, anti-coloring agents, oxidation, and the like within a range not impairing the object of the present invention. Additives such as inhibitors, heat-resistant agents, plasticizers, lubricants, weathering agents, colorants, and pigments can be added.

  The long fibers according to the present invention are formed by melt spinning using a conventional spinneret. To blend a polylactic acid polymer and an aliphatic polyester copolymer, there are a method of making a polylactic acid polymer into a master batch, a method of mixing by dry blending, etc., but the dry blend method is adopted from the viewpoint of cost. It is preferable to do. Further, the structure of the long fiber needs to be a sea-island structure in which a polylactic acid-based polymer forms a sea part and an aliphatic polyester copolymer forms an island part.

  The 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. 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 fineness of the long fibers according to the present invention is preferably 1.0 to 4.0 dtex, more preferably 1.0 to 3.0 dtex. If the fineness is less than 1.0 dtex, the fiber cannot sufficiently withstand the tension of the ejector during spinning, and part of the fiber may be cut off. Further, when the fineness is 4.0 dtex or less, when it is made into a non-woven fabric and used as a food filter, the amount of powder leakage is small and suitable as a filter material.

  The biodegradable long-fiber nonwoven fabric of the present invention has a structure in which sea-island blend long-fiber webs containing a low-melting-point and low-crystallinity component are integrated by thermocompression, so that the bonding between fibers is strong. High rigidity and mechanical strength and heat seal strength can be obtained, and a structure with discontinuous low melting point and low crystalline components in the surface layer causes "rolling" during thermocompression. It is difficult to obtain characteristics such as excellent dimensional stability.

  The thermocompression bonding of the long-fiber nonwoven fabric of the present invention can use a pair of heating rolls composed of an embossing roll and a flat roll having an uneven surface structure. When thermocompression bonding is performed using an embossing roll, it is preferable that thermocompression bonding is performed at a thermocompression area ratio in a range of 5 to 40%, more preferably 5 to 30%, and even more preferably. 5 to 20%. When the thermocompression area ratio is within this range, it is possible to perform a good thermocompression treatment between fibers, which is preferable in terms of achieving appropriate mechanical strength and rigidity, air permeability, and powder leakage of the nonwoven fabric obtained.

  The thermocompression treatment temperature and pressure should be appropriately selected according to conditions such as the basis weight and speed of the web to be supplied, and are not generally determined, but are 10 to 80 ° C. higher than the melting point of the polylactic acid polymer. It is preferably a low temperature, more preferably a temperature lower by 20 to 50 ° C., and further preferably a temperature lower by 20 to 40 ° C. The fluff rating needs to be 2.5 or higher, and preferably 3 or higher.

  The powder leakage rate of the biodegradable long fiber nonwoven fabric of the present invention is preferably 10 wt% or less, more preferably 7.5 wt% or less, and still more preferably 5.0 wt% or less. When the powder leakage rate is 10 wt% or less, the shielding properties and retention of fine particles and powders are excellent. When the powder leakage rate exceeds 10 wt%, the amount of powder leakage increases when used as a food filter, which is not suitable as a filter.

  The boiling water shrinkage ratio of the biodegradable long fiber nonwoven fabric of the present invention is 5% or less, preferably 3% or less. When the boiling water shrinkage is 5% or less, there is almost no shrinkage due to thermoforming and the like, 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 heat seal strength of the biodegradable long fiber nonwoven fabric of the present invention is 1.5 N / 25 mm or more, preferably 2.0 N / 25 mm or more. When the heat seal strength is less than 1.5 N / 25 mm, the seal portion is easily peeled off, causing problems such as leakage of contents to the outside.

  The transparency of the biodegradable long fiber nonwoven fabric of the present invention is 50% or more, preferably 55% or more, more preferably 60% or more. If the transparency is less than 50%, 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 of the present invention is preferably 10 to 50 g / m ² , more preferably 12 to 30 g / m ² , and still more preferably 12 to 20 g / m ² . If the basis weight is less than 10 g / m ² , the transparency is good, but the fiber gap is large and powder leakage is easy, and the mechanical strength is insufficient. On the other hand, if the basis weight exceeds 50 g / m ² , the amount of powder leakage However, transparency and component extractability are poor.

  The thickness of the biodegradable long fiber nonwoven fabric of 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, powder leakage and component extractability can be obtained when used as a food filter.

The average apparent density of the biodegradable long-fiber nonwoven fabric of the present invention is preferably 0.05~0.50g / cm ^3, more preferably from 0.10~0.30g / cm ^3, more preferably 0.10 ˜0.25 g / cm ³ . The average apparent density is related to the rigidity, powder leakage and component extractability of the nonwoven fabric, and within this range, it is excellent in processability into a bag shape as a food filter and powder leakage. When the average apparent density is less than 0.05 g / cm ³ , the fiber gap becomes large, so the amount of powder leakage is large and the nonwoven fabric has insufficient rigidity. On the other hand, when the average apparent density exceeds 0.50 g / cm ³ , the fiber gap However, the powder extractability is improved, but the component extractability is deteriorated, and the required performance as a food filter cannot be achieved.

The tensile strength of the biodegradable long fiber nonwoven fabric of the present invention is preferably 200 N / 50 mm or more, more preferably 210 N / 50 mm or more when converted to 100 g / m ² basis weight in the MD direction. When the tensile strength is within this range, it is excellent in production stability at the time of bag making processing, tear prevention at the time of use as a food filter, and the like.

  The spinning speed when producing the long fibers according to the present invention is preferably 3000 to 8000 m / min, more preferably 4000 to 7000 m / min. If the pulling speed when pulling the spun yarn is within the above range, a polylactic acid polymer can be sufficiently oriented and crystallized to obtain a nonwoven fabric excellent in mechanical properties and dimensional stability, and There is little possibility of yarn breakage during spinning, which is preferable from the viewpoint of the productivity of the nonwoven fabric.

  The birefringence Δn of the long fiber according to the present invention is preferably 0.012 to 0.025, and more preferably 0.014 to 0.022. When the birefringence is within this range, a nonwoven fabric having an appropriate orientation crystallinity of fibers and excellent mechanical strength and dimensional stability can be obtained.

  The degree of crystallinity of the long fibers according to the present invention is preferably 30 to 60%, more preferably 35 to 60%. When the crystallinity is within this range, a fiber excellent in mechanical strength and dimensional stability can be obtained.

  The biodegradable long-fiber non-woven fabric of the present invention may be provided with conventional post-processing, for example, a deodorant, an antibacterial agent, an acaricide, etc., as long as the effects of the present invention are exhibited. Dyeing, water repellent treatment, water permeable treatment, moisture permeable waterproof treatment, etc. may be applied.

  The biodegradable long-fiber nonwoven fabric of the present invention is very suitable as a food filter for green tea, black tea, coffee, etc. due to its excellent transparency and clear contents and excellent powder leakage It has the characteristics. 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 three-dimensional 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 long fiber nonwoven fabric of the present invention is stiff and has an appropriate rigidity, and thus has excellent shape recoverability.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not intended to be limited to the examples.
First, a measurement method and an evaluation method will be described.
(1) Weight per unit area (g / m ² ): In accordance with JIS L-1906, three test pieces of 20 cm in length and 25 cm in width were sampled per 1 m width of the sample, the mass was measured, and the average value per unit area It was calculated in terms of mass.
(2) Thickness: The thickness at a load of 100 g / cm ² was measured by the method specified in JIS L-1906.
(3) Average apparent density (g / cm ³ ): From the basis weight and thickness measured by the method defined in JIS L-1906, the mass per unit volume was determined by the following formula, and the average of three locations per 1 m width of the sample I asked for it.
Average apparent density (g / cm ³ ) = (weight per unit g / m ² ) / ((thickness mm) × 1000)

(4) Fineness (dtex): The weight of 1 m length was measured, the average value of n = 5 was calculated | required, and it calculated and calculated to 10000 m length.
(5) MFR (g / 10 min): Melt indexer (manufactured by Toyo Seiki Co., Ltd .: MELT INDEXER S-101) using a melt flow device, an orifice diameter of 2.095 mm, an orifice length of 0.8 mm, according to JIS K-7210, The discharge amount (g) of molten polymer per 10 minutes was calculated and determined from the time required to discharge a constant volume under the conditions of a load of 2.16 kg and a measurement temperature of 230 ° C.
The melt flow ratio is expressed by the following formula:
Melt flow rate ratio = [(MFR of aliphatic polyester copolymer) / (MFR of polylactic acid copolymer)]
Calculated by

(6) Boiling water shrinkage rate (%): In accordance with JIS L-1906, three 25 cm long x 25 cm wide test specimens were collected per 1 m width of the sample, immersed in boiling water for 3 minutes, and after natural drying, MD direction Then, the shrinkage rate in the CD direction is obtained. 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.

(7) Transparency (%): The reflectance (L value) is measured with a Macbeth spectrophotometer (CE-7000A type: manufactured by Sakata Ink), and the L value (Lw0) of the standard white board and the L value (Lb0) of the standard blackboard ) Was used as a reference, and transparency was determined according to the following formula from the L value (Lb) placed on a blackboard like the L value (Lw) placed on the white plate.
Transparency (%) = {(Lw−Lb) / (Lw0−Lb0)} × 100

(8) 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 of the photographs, and the average value was calculated as 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.

(9) Powder leakage rate (wt%): About 2g of 7 kinds of dust for JIS Z-8901 test was weighed, and its weight W1 (g) was measured and placed on the nonwoven fabric. Then, the dust weight W2 (g) that passed through the nonwoven fabric was measured and determined by the following formula.
Powder leakage rate (wt%) = (W2 / W1) × 100

(10) Tensile strength (N / 50 mm): Using an autograph AGS-5G type manufactured by Shimadzu Corporation, a 50 mm wide sample is grasped and stretched at a length of 100 mm and a tensile speed of 300 mm / min. The strength was measured and the measurement was performed five times in the MD direction of the nonwoven fabric, and the average value was obtained.

(11) Heat seal strength (N / 25 mm): Using a Autograph AGS-5G model manufactured by Shimadzu Corporation, the heat seal portion of a 25 mm width sample is peeled off and attached approximately 50 mm in the vertical direction, grasping length 50 mm, and 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.

(12) 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.

(13) Crystallinity (%): Using a differential scanning calorimeter DSC2920 manufactured by TA Instruments, the heating rate is 10 ° C./min, the temperature is raised from 30 ° C. to 200 ° C., and the crystallization heat generation ΔHc The amount of heat of crystal melting ΔHm was measured. The degree of crystallinity (%) was determined by the following formula.
Crystallinity χc (%) = (ΔHm−ΔHc) / 93 × 100
Here, 93 J / g is the heat of fusion of a complete crystal of polylactic acid.

(14) Biodegradability: The non-woven fabric was embedded in the soil, taken out after 6 months, and biodegradability was evaluated according to the following evaluation criteria according to the shape retention property or the breaking strength retention rate of the nonwoven fabric.
○: The shape of the nonwoven fabric is not maintained, or the breaking strength is reduced to 50% or less with respect to the initial value.
X: The breaking strength exceeds 50% with respect to the initial value.

(15) Fluff grade: 25 mm x 300 mm test pieces are taken in the MD and CD directions, using a Japan Society for the Promotion of Science type fastness tester, the load of the friction element is 200 g, and the same cloth is used on the friction element side The fluff resistance was graded according to the following evaluation criteria.
1.0 grade: The fiber is peeled off as the test piece breaks.
2.0 grade; the thinner the specimen, the more severe the fiber is peeled off.
Grade 2.5: The pills are large and clearly visible, and the fibers begin to float at multiple locations.
3.0 grade: A clear hairball starts to appear or a plurality of small hairballs are seen.
Grade 3.5: Fluffy so that there are about 3 to 5 fibers, or small fluffs start to form in several places.
4.0 grade: Fluffed to the extent that there are about 1 to 2 fibers, or a small fluff begins to form in one place.
Grade 5.0: No fuzz.

Next, the present invention will be specifically described with reference to examples and comparative examples.
[Example 1]
Polybutylene succinate having a melting flow ratio of 1.1 is mixed with a polylactic acid polymer having a melting point of 167 ° C. and an MFR of 44 g / 10 min by dry blending so that the addition amount is 10 wt%, and ordinary melt spinning is performed. Supplied to the device. Next, the mixture was uniformly melt-mixed at 230 ° C., and melt spun from a spinneret having a spinning hole with a circular cross section at a spinning speed of 4600 m / min to obtain a polylactic acid-based blend long fiber having a fineness of 2.0 dtex. This fiber is spread and dispersed to prepare a web having a basis weight of 20 g / m ² , and a partially decomposable thermocompression nonwoven fabric is obtained by thermocompression bonding with an area ratio of 7.1% between the embossing roll and the flat roll. It was. 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 blending was performed so that the addition rate of polybutylene succinate was 6.0 wt% 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 blending was performed so that the addition rate of polybutylene succinate was 3.0 wt% in Example 1. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 4]
In Example 1, blending was performed so that the addition rate of polybutylene succinate was 3.0 wt%, and a polylactic acid-based blend long fiber having a fineness of 2.4 dtex was opened and dispersed to produce a web having a basis weight of 40 g / m ^2. A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 5]
A polybutylene succinate having a melt flow ratio of 1.1 is mixed with a polylactic acid polymer having a melting point of 167 ° C. and an MFR of 44 g / 10 min by dry blending so that the addition rate is 1.0 wt%. It was supplied to a melt spinning apparatus. Next, the mixture was uniformly melt-mixed at 230 ° C., and melt spun from a spinneret having a spinning hole with a circular cross section at a spinning speed of 6000 m / min to obtain a polylactic acid-based blend long fiber having a fineness of 1.3 dtex. This fiber was spread and dispersed to produce a web having a basis weight of 16 g / m ² , and a biodegradable long fiber nonwoven fabric was obtained by partial thermocompression bonding between an embossing roll and a flat roll at a thermocompression area ratio of 7.1%. . 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 5 except that partial thermocompression bonding was performed at a thermocompression bonding area ratio of 11.4% in Example 5. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 7]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 5 except that partial thermocompression bonding was performed at a thermocompression bonding area ratio of 14.4% in Example 5. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 8]
A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 5 except that partial thermocompression bonding was performed at a thermocompression bonding area ratio of 30.0% in Example 5. The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Example 9]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 5 except that the polylactic acid-based blend long fiber having a fineness of 2.0 dtex in Example 5 was partially thermocompression bonded at a thermocompression area ratio of 11.4%. . The physical properties of the obtained nonwoven fabric are shown in Table 1 below.

[Comparative Example 1]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that polybutylene succinate was not added in Example 1. The physical properties of the obtained nonwoven fabric are shown in Table 1 below. Due to poor thermocompression bonding, heat seal strength and tensile strength were poor.

[Comparative Example 2]
A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that polybutylene succinate having a melt flow ratio of 2.0 in Example 1 was blended. The physical properties of the obtained nonwoven fabric are shown in Table 1 below. Since the melt flow ratio was high, the effect of suppressing orientation crystallization was small, and the heat seal strength and tensile strength were poor.

[Comparative Example 3]
In Example 1, except that the polybutylene succinate resin was blended so that the addition rate was 15 wt%, an attempt was made to obtain a biodegradable long-fiber nonwoven fabric in the same manner as in Example 1, The yarn was bent in the vicinity of the spinneret and the spinning was impossible, and a continuous yarn could not be obtained.

[Comparative Example 4]
A biodegradable long fiber nonwoven fabric was obtained in the same manner as in Example 5 except that the polylactic acid-based blend long fiber having a fineness of 5.0 dtex in Example 5 was partially thermocompression bonded at a thermocompression area ratio of 11.4%. . The physical properties of the obtained nonwoven fabric are shown in Table 1 below. Since the spinning speed was low and the fineness was large, the boiling water shrinkage was high, the powder leakage was high, and the filter performance was poor.

[Comparative Example 5]
In Example 1, blending was performed so that the addition rate of polybutylene succinate was 3.0 wt%, and a polylactic acid-based blend long fiber having a fineness of 2.4 dtex was opened and dispersed to create a web having a basis weight of 60 g / m ^2. A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that. The physical properties of the obtained nonwoven fabric are shown in Table 1 below. Due to the high basis weight, the transparency was low, and because the air permeability was low, the filter was poor in extractability.

[Comparative Example 6]
A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 1 except that blending was performed so that the addition rate of polybutylene succinate having a melt flow ratio of 0.1 in Example 1 was 3.0 wt%. However, many yarn breaks occurred and yarn bending occurred near the spinneret, and spinning was not possible, and a continuous yarn could not be obtained.

[Comparative Example 7]
In the same manner as in Example 1, except that blending was performed so that the addition rate of polybutylene succinate was 3.0 wt% in Example 1 to produce a polylactic acid-based blend continuous fiber having a fineness of 0.6 dtex. A degradable long fiber nonwoven fabric was obtained. The physical properties of the obtained nonwoven fabric are shown in Table 1 below. Since the fineness was too small, the transparency was poor and the filter performance was poor.

[Example 8]
A biodegradable long-fiber nonwoven fabric was obtained in the same manner as in Example 5 except that partial thermocompression bonding was performed at a thermocompression bonding area ratio of 3.0% in Example 5. The physical properties of the obtained nonwoven fabric are shown in Table 1 below. The heat seal strength and tensile strength were poor because the area ratio of thermocompression bonding was low and the thermocompression bonding of the web was incomplete.

  The biodegradable long-fiber non-woven fabric of the present invention has less fuzz and is excellent in mechanical strength and powder leakage, transparency, etc. Wiping cloth, draining bags, sheets, bedspreads, heating element packaging materials, dry packaging materials, food packaging materials, etc., automobile interior materials such as mats, sound absorbing materials, ceiling materials, seat lining fabrics, air conditioning filters It is preferably used for industrial materials such as dust collecting filter materials, and sanitary materials such as disposable diapers. In particular, it can be suitably used in the field of food filters used for green tea, black tea, coffee, soup stock and the like.

Claims (8)

What added 0.5-10 wt% of aliphatic polyester copolymer whose melting | fusing point is 140 degrees C or less with respect to 100 wt% of polylactic acid-type polymer whose melting | fusing point is 150 degreeC or more is what this polylactic acid-type polymer and this fat have. The melt flow ratio of the aliphatic polyester copolymer is obtained by melt spinning in the range of 0.2 to 1.5, the polylactic acid-based polymer forms a sea portion, and the aliphatic polyester copolymer is an island portion. the sea-island composite long fibers forming the at 5-40% thermocompression bonding area ratio, obtained by integrally thermocompression bonding, birefringence exceeds 0.012, boiling water shrinkage percentage is 5% or less, a heat A biodegradable long-fiber nonwoven fabric having a sealing strength of 1.5 N / 25 mm or more and transparency of 50% or more.   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, The polymer is 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 at least the types of the polymer. The biodegradable long fiber nonwoven fabric described.   The biodegradable long-fiber nonwoven fabric according to claim 1 or 2, wherein the aliphatic polyester copolymer is polybutylene succinate. Wherein the biodegradable length Ri der powder leakage rate is less than 10% of the non-woven fabric, One or is fluff grade 2.5 or higher grade, biodegradable length according to any one of claims 1 to 3 Fiber nonwoven fabric. Basis weight of the biodegradable long-fiber nonwoven fabric is 10 to 50 g / m ^2, and thickness of 0.02～0.50Mm, biodegradable length according to any one of claims 1 to 4 Fiber nonwoven fabric. Tensile strength when converted to the MD direction of 100 g / m ² basis weight of said biodegradable filament nonwoven fabric is 200 N / 50 mm or more, a biodegradable filament nonwoven fabric according to any one of claims 1 to 5 .   The long fiber is pulled and spun at a spinning speed of 3000 to 8000 m / min, has a fineness of 1.0 to 4.0 dtex, and a crystallinity of 30 to 60%. The biodegradable long fiber nonwoven fabric according to any one of the above.   The filter for foodstuffs containing the biodegradable long-fiber nonwoven fabric of any one of Claims 1-7.