JP2005048350A - Biodegradable nonwoven fabric and sanitary material, wrapping material and agricultural material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide a nonwoven fabric having biodegradable property and soft feeling and good character, especially to provide a sanitary material, a wrapping material and an agricultural material. <P>SOLUTION: The nonwoven fabric comprises at least two accumulated layers of a biodegradable filament nonwoven fabric A having fiber diameter of 8-15μm and 6-10 g/m<SP>2</SP>of basis weight and a biodegradable filament nonwoven fabric B having fiber diameter of 2-8μm and 2-6 g/m<SP>2</SP>of basis weight. The nonwoven fabric has 12-30% of the weight ratio of the nonwoven fabric B, and is partially thermo-compression bonded and if necessary, is subjected to a softening treatment such as mechanical rubbing process, etc. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is applied to various medical hygiene materials, packaging materials and agricultural materials such as disposable diapers, sanitary napkins, and surgical clothes having biodegradability and excellent mechanical strength and flexibility, and good quality and texture. The present invention relates to a suitable non-woven fabric, and further relates to a medical hygiene material, a packaging material and an agricultural material using the same.

  Conventionally, resins such as polyethylene, polypropylene, polyester, and polyamide have been used for nonwoven fabrics for medical hygiene materials, packaging materials, and agricultural materials. However, nonwoven fabrics obtained from these resins are not self-degradable and have a natural environment. It is extremely stable.

  For this reason, used medical hygiene materials are incinerated or landfilled in an incinerator, but incineration is not only expensive, but also causes environmental problems such as impact on the atmosphere during incineration. there is a possibility. In addition, landfill processing is becoming a major social problem from the viewpoint of the destruction of the natural environment, and the early development of naturally-friendly medical hygiene materials and the like is desired.

  In order to cope with these, non-woven fabrics using viscose rayon short fibers obtained by a dry or solution dipping method, rayon long fiber nonwoven fabrics obtained by a wet spunbond method, natural fibers such as chitin and atelocollagen, and natural origins It is known to use various biodegradable nonwoven fabrics such as a nonwoven fabric made of chemical fibers or a spunlace nonwoven fabric made of cotton.

  However, these conventional biodegradable non-woven fabrics have low mechanical strength of fibers constituting the non-woven fabric and are hydrophilic, so that the strength is greatly reduced during water absorption and wetting, and the shrinkage during wetting and drying is large. There is a problem of lack of dimensional stability of the material, and there is also a problem that the material itself is a non-thermoplastic resin, so it does not have thermal adhesiveness, so it is impossible to use heat sealability during fabric processing Therefore, there is a problem that it cannot be employed practically.

  In order to improve these problems, it consists of a large number of long fibers melt-spun with an aliphatic polyester resin that is thermoplastic and can be decomposed by microorganisms, and the aliphatic polyester resin constitutes a glycol and an aliphatic dicarboxylic acid or a derivative component thereof. A biodegradable nonwoven fabric having a fineness of 1 to 10 denier and a method for producing the same are disclosed (Patent Document 1).

  However, this non-woven fabric has not yet reached a point where both spinnability and biodegradability can be satisfied in practice. That is, as an aliphatic polyester suitable for melt spinning and usable for a long-fiber nonwoven fabric, a polybutylene succinate polymer synthesized from 1,4-butadiol and succinic acid has good melt spinnability and excellent strength and texture. A biodegradable long-fiber nonwoven fabric can be obtained, but there are problems such as a slow biodegradation rate.

  In addition, a means for improving the situation and imparting liquid permeability, which is a necessary characteristic as a nonwoven fabric for sanitary materials, to the nonwoven fabric with a good balance of flexibility and texture while having excellent biodegradability has been proposed ( Patent Document 2).

  That is, after the polybutylene succinate polymer synthesized from 1,4-butadiol and succinic acid is made high molecular weight by urethane bond, the resulting resin composition comprising an aliphatic polyester having thermoplasticity is formed with a modified cross-section die. It is heated and melted separately in an extrusion spinning machine equipped with a circular cross-section die, extruded from a large number of die and spun, and the spun continuous filaments are stretched with high-speed air from an ejector and applied to a collision plate. Opening, then collecting and depositing on a support to form webs each having a specific range of fineness and basis weight, and laminating these webs, The web is formed by spraying, drying, and forming a entangled web, and the web is partially and regularly provided with a heat fusion zone by heat embossing. Proposals for spunbonded non-woven fabric is. The non-woven fabric has a mixture of long and thin filaments having a circular cross section and an irregular cross section in the thickness direction of the non-woven fabric, whereby the non-woven fabric has biodegradability and balances excellent flexibility, texture, strength, liquid permeability and the like. It has been proposed that it can be well prepared.

However, this nonwoven fabric, medical sanitation materials, especially in the case of a disposable diaper applications, conventional polypropylene, basis weight in the spunbond thermal bonding articles such as polyethylene compared to a 15g / m ² ~25g / m ² Te, due to the high and 30g / m ² ~50g / m ² basis weight, also in the long-fiber nonwoven fabric, injects high-pressure water jet stream from the web surface by laminating a circular cross-section filaments and irregular cross section filaments, texture manner be dried It was not satisfactory.

  In particular, after jetting, drying and entanglement and integration of a high-pressure water jet stream, the web is partially heat-sealed by heat embossing treatment, so that the density of the nonwoven fabric is increased and the rigidity is increased by the thermal bonding. It was not satisfactory in terms of flexibility and texture.

Further, since the single yarn fineness of polylactic acid-based long fiber is to adjust the basis weight of the nonwoven fabric 15g / m ² ~30g / m ² at 1.5 to 3.5 dtex, 400~1400cm ³ / cm ² air permeability It is proposed that a non-woven fabric for hygiene material having both water permeability and flexibility can be obtained by setting to / sec (Patent Document 3). However, it can be satisfied as a non-woven fabric for sanitary materials simply by setting the single yarn fineness to 1.5 to 3.5 dtex, the basis weight to 15 to 30 g / m ² and the air permeability to 400 to 1400 cm ³ / m ² / sec. Not. That is, as non-woven fabrics for sanitary materials and the like, there is a strong demand for non-woven fabrics with small unevenness in weight, high flexibility and appropriate physical properties, and air permeability is 400 to 1400 cm ³ / m ² / sec. However, since the air permeability is high and the water pressure resistance is too low according to the knowledge of the present inventors, urine leakage tends to occur and it cannot be used practically.
JP-A-8-060513 JP-A-10-219556 Japanese Patent Laid-Open No. 2002-242068

  The object of the present invention is to achieve the above-mentioned problems, biodegradable, flexible texture, moderate mechanical strength, low spot weight, high quality, high quality medical hygiene material, packaging material or agricultural material And a medical hygiene material, a packaging material, or an agricultural material using the nonwoven fabric.

  The inventors of the present invention have reached the present invention as a result of intensive studies to solve the above problems.

That is, the present invention has the following configurations (1) to (9).
(1) The biodegradable long-fiber nonwoven fabric A having a fiber diameter of 8 μm to 15 μm and a basis weight of 6 to 10 g / m ² , and an average fiber diameter of 2 μm to 8 μm and a basis weight of 2 to 2 A nonwoven fabric characterized by comprising a structure in which at least two types of nonwoven fabrics of biodegradable long-fiber nonwoven fabric B of 6 g / m ² are laminated.
(2) The nonwoven fabric according to (1), wherein the nonwoven fabric A is a spunbonded nonwoven fabric, and the nonwoven fabric B is a meltblown nonwoven fabric.
(3) The fiber diameter variation rate of the nonwoven fabric B constituting the laminated nonwoven fabric is 30 to 60%, and the weight ratio of the nonwoven fabric B in the laminated nonwoven fabric is 12 to 30%. The nonwoven fabric according to (1) or (2).
(4) The biodegradable nonwoven fabrics A and B are partially thermocompression bonded, and the total area of the partial thermocompression bonding portions is 8 to 30% of the whole (1) to (3) ) The nonwoven fabric according to any one of
(5) The above-mentioned (1) to (4), wherein the biodegradable nonwoven fabric has a bending resistance (measured in the vertical direction) measured by JIS-L-1096A method (45 ° cantilever method) of 30 to 65 mm. The nonwoven fabric in any one of.
(6) The polymers constituting the biodegradable nonwoven fabric A and the biodegradable nonwoven fabric B have substantially the same melting point, or the difference in melting point is within 50 ° C. The nonwoven fabric according to any one of 5).
(7) The above-described (1), wherein the nonwoven fabric constituting the biodegradable nonwoven fabric A and the biodegradable nonwoven fabric B is composed of polylactic acid or polybutylene succinate, or a combination thereof. The nonwoven fabric in any one of-(6).

The medical hygiene material of the present invention has the following configuration (8).
(8) A medical hygiene material comprising the non-woven fabric according to any one of (1) to (7) above.
The packaging material of the present invention has the following configuration (9).
(9) A packaging material comprising the nonwoven fabric according to any one of (1) to (7) above.
The agricultural material of the present invention has the following configuration (10).
(10) An agricultural material comprising the nonwoven fabric according to any one of (1) to (7) above.

  INDUSTRIAL APPLICABILITY According to the present invention, a non-woven fabric suitably used for medical hygiene materials, packaging materials, or agricultural materials that is biodegradable, has a soft texture, moderate mechanical strength, has less spotted spots, and has high quality and high quality. And a medical hygiene material, a packaging material, or an agricultural material using the nonwoven fabric.

The fibers constituting the nonwoven fabric of the present invention have a fiber diameter of 8 μm to 15 μm and a biodegradable long-fiber nonwoven fabric A having a basis weight of 6 to 10 g / m ² and a fiber diameter of 2 μm to 8 μm. This is a nonwoven fabric having a configuration in which at least two types of nonwoven fabrics of biodegradable long-fiber nonwoven fabric B having a basis weight of 2 to 6 g / m ² are laminated.

  Examples of the biodegradable resin used in the present invention include polylactic acid resin, polybutylene succinate resin, polycaprolactone resin, polyethylene succinate resin, polyglycolic acid resin, polybutylene terephthalate resin, and polyhydroxybutyrate resin. Is mentioned. Among them, polylactic acid resin is preferable because it is made from natural plants and is the most naturally-friendly biodegradable resin.

  Polylactic acid is a polyester mainly composed of L-lactic acid, and may be a polyester containing 60% or more of L-lactic acid and containing D-lactic acid within a range not exceeding 40%.

  Polylactic acid can be produced by using a two-stage lactide method in which lactide, which is a cyclic dimer, is first produced from lactic acid as a raw material, and then ring-opening polymerization, and direct dehydration condensation in a solvent using lactic acid as a raw material. A step direct polymerization process is known.

When polylactic acid is used in the present invention, the polylactic acid may be obtained by any method. In the case of a polymer obtained by the lactide method, since the cyclic dimer contained in the polymer is vaporized at the time of melt spinning and causes irregular yarn spinning, etc., the cyclic dimer contained in the polymer before melt spinning. The content of is preferably reduced as much as possible, and is preferably 0.1 wt% or less. Further, in the case of the direct polymerization method, there is substantially no problem due to the cyclic dimer, so that it can be said that it is more preferable from the viewpoint of yarn production. Since polylactic acid has high biodegradability or hydrolyzability, it has an advantage that it is easily decomposed in the natural environment. In the case of the spunbond method, the polylactic acid has a weight average molecular weight in the range of 100,000 to 300,000, more preferably in the range of 100,000 to 200,000. This is because if the weight average molecular weight is less than 100,000, the strength of the fiber is lowered, and it becomes difficult to sufficiently bring out the strength of the nonwoven fabric. In addition, if the weight average molecular weight is greater than 300,000, the filament spun from the die is not spun even if it is pulled by air soccer, etc., so high-speed spinning is not possible, and the operability is good but undrawn yarn This is because it becomes like, making it difficult to obtain sufficient fiber strength, and the strength as a nonwoven fabric may be insufficient.

  The polylactic acid used for the melt blown nonwoven fabric has a weight average molecular weight of 150,000 or less, preferably 30,000 to 100,000, and more preferably 30,000 to 70,000. If the weight average molecular weight is greater than 150,000, the melting temperature cannot be increased to 240 ° C. or higher due to the thermal decomposability when polylactic acid is melted. It becomes difficult to stably obtain ultrafine fibers having a diameter of 10 μm or less, and therefore, it becomes difficult to obtain ultrafine fibers having a fiber diameter of 2 to 8 μm necessary for the nonwoven fabric B.

  The fiber diameter of the filament constituting the biodegradable nonwoven fabric A is preferably 8 μm to 15 μm, more preferably 8 μm to 13 μm. When the fiber diameter is larger than 15 μm, it is advantageous in terms of yarn production, but as the fiber diameter increases, the number of fibers constituting the non-woven fabric decreases, and the spot weight increases, and the air permeability and water permeability are Although it improves, non-woven fabrics for medical hygiene materials, such as disposable diapers, have partial breathability due to increased spot weight, water permeability spots, soft spots, tensile strength spots, low basis weight In some cases, a satisfactory product cannot be obtained due to problems such as easy generation of fluff due to poor bonding of the portion. When the fiber diameter is less than 8 μm, it is difficult to obtain a non-woven fabric that is of good quality and quality, such as when single-thread breakage occurs due to poor operability due to insufficient spinnability when pulling at high speed with air soccer. come.

Further, the fiber diameter constituting the biodegradable nonwoven fabric B is preferably in the range of 2 μm to 8 μm, and when the fiber diameter is larger than 8 μm, the cooling of the filament becomes insufficient. As a result, there is a problem that the uniform nonwoven fabric, which is characteristic of the melt blown nonwoven fabric, cannot be obtained due to web disturbance on the collection net due to poor collection performance. It is not preferable.
When the fiber diameter is less than 2 μm, there may be a case where a product satisfying quality is not obtained, for example, the yarn-making property is deteriorated and polymer defects called shots are frequently generated.

  The biodegradable nonwoven fabric A and the biodegradable nonwoven fabric B are preferably laminated at least two layers, more preferably the nonwoven fabric B is an intermediate layer and the nonwoven fabric A is arranged on both the front and back sides. If it is configured, it is possible to obtain a better product in terms of improvement in the strength level of the nonwoven fabric, fluff resistance and lint-free property, and further, biodegradation with different fineness, cross-sectional shape or biodegradable polymer species as necessary A non-woven fabric that is superior in both functionality and quality by laminating the porous spunbonded nonwoven fabrics A1 and A2, further laminating the biodegradable meltblown nonwoven fabrics B1 and B2, and subsequently laminating A1 and A2. It can be.

Basis weight after the lamination of the biodegradable nonwoven fabric A and a biodegradable nonwoven fabric B may have 10 to 25 g / m ^2, more preferably 15 to 20 g / m ^2, and most preferably 16~18g / m ^2. When the basis weight of the nonwoven fabric exceeds 25 g / m ² , a product that is strong and satisfactory can be obtained. However, when the product is finished as a medical hygiene material, packaging material, or agricultural material because it has high rigidity and lacks flexibility. In some cases, it may be unsuitable for practical use, such as being unpleasant to the touch. In addition, when the basis weight is less than 10 g / m ² , there arises a problem that tearing due to insufficient strength due to partial spot weight may occur.

  Among the laminated nonwoven fabrics composed of the spunbond nonwoven fabric A and the melt blown nonwoven fabric B, the composition ratio of the nonwoven fabric B is preferably in the range of 12 to 30%, more preferably 13 to 25%. When the composition ratio is less than 12%, the effect of improving the spot weight is low. For example, when used for a side gather of a paper diaper, the water pressure is insufficient, and it is difficult to obtain a satisfactory nonwoven fabric. Further, when the composition ratio is larger than 30%, not only the strength as a nonwoven fabric is lowered, but also the nonwoven fabric B having a very high thermal shrinkage rate that lacks crystal orientation is thermally shrunk during emboss bonding, and wrinkles. It is difficult to obtain a material that is satisfactory as a medical hygiene material, packaging material or agricultural material.

  The lamination method of the non-woven fabric A and the non-woven fabric B is performed using an in-line fabric production facility in which a spunbond nonwoven fabric production facility and a melt blown nonwoven fabric production facility, which can be formed into a sheet over the entire width in the width direction, are connected to at least two layers. Can be manufactured.

  Moreover, it is preferable that melting | fusing point of resin which comprises biodegradable nonwoven fabric A and biodegradable nonwoven fabric B is substantially the same, or both melting | fusing point difference is 50 degrees C or less, More preferably, the nonwoven fabric A The melting point of the non-woven fabric B is lower than the melting point at a level within 50 ° C., more preferably the melting point of the non-woven fabric B is lower than the melting point of the non-woven fabric A at a level within 40 ° C. .

  When the difference in melting point between the nonwoven fabric A and the nonwoven fabric B is greater than 50 ° C., delamination between the laminated nonwoven fabric A and the nonwoven fabric B is likely to occur, and a satisfactory medical hygiene material, packaging material, or agricultural material is obtained. In addition, even if there is no delamination, the non-woven fabric (B) having a low melting point has a strong thermal bond and may become a hard non-woven fabric as a texture.

Spots on the nonwoven fabric are extremely important characteristics for nonwoven fabrics for medical hygiene materials, packaging materials, or agricultural materials, and greatly affect the tensile strength, moisture permeability, liquid permeability, rigidity, etc. of the nonwoven fabric. When the basis weight of the nonwoven fabric is 25 g / m ² or less, the basis weight is preferably 9% or less. For example, when the basis weight is 25 g / m ² and the basis weight is 9%, the portion with a low basis weight is 20 g / m ² or less, and although the texture of the portion is soft, the tensile strength is low and the adhesive strength is also low. For this reason, fluff is generated, and the portion having a high basis weight is 30 g / m ² or more, and the rigidity becomes too high, which is insufficient as a sanitary material, packaging material or agricultural material. Moreover, when the fabric weight of a nonwoven fabric is less than 10 g / m < ² >, the tensile strength of a low fabric weight part is too low, and it cannot endure use, and is unpreferable.

  The biodegradable long-fiber nonwoven fabric A of the present invention may be a filament composed of a single component of a biodegradable resin, a biodegradable fiber and a core in which a low melting point resin is a sheath component and a high melting point resin is a core component. It may be a mixed filament with the same biodegradable fiber as the component resin, or a single-use nonwoven fabric of the core-sheath type composite fiber.

  In the case of a laminated nonwoven fabric of biodegradable spunbond and biodegradable meltblown, it is necessary to use the same kind of biodegradable resin as the resin constituting the surface layer resin of the filament constituting the spunbond nonwoven fabric and the meltblown nonwoven fabric. This is effective in improving the adhesion stability such as elimination of delamination of the nonwoven fabric after pressure bonding.

  As a method for thermocompression bonding of the filaments constituting the nonwoven fabric, any conventional method such as a hot air-through method, an ultrasonic method, or an embossing method can be bonded without any particular problem. The thermocompression bonding temperature by the embossing method is preferably a temperature that is 10 ° C to 50 ° C lower than the melting point of the resin that forms the filament surface, and more preferably a temperature that is 15 ° C to 40 ° C lower. When the embossing temperature is lower than the melting point of the resin forming the filament surface by less than 10 ° C., the resin melts severely, the sheet is taken on the embossing roll, roll contamination occurs, the sheet becomes hard, and the roll is also wound. Stable production such as frequent occurrence is also impossible. Further, when the temperature is 50 ° C. or more lower than the melting point of the filament surface resin, the resin is insufficiently welded and soft in texture, but there are many problems such as weak physical properties. The embossing roll should have a pressure bonding area in the range of 8% to 30%, and any pattern can be engraved on the roll, but both the upper and lower rolls are more engraved from the standpoint of widening the bonding temperature range. preferable. Further, in the present invention, when inorganic particles such as titanium oxide, silicon dioxide, or calcium carbonate, or a lubricant such as ethylene bisstearamide is added within a range in which the effects such as the spinning property and physical properties are not impaired, the embossing roll and the adhesive are bonded. The sheet releasability is improved, more stable adhesion is obtained, and the non-woven fabric can be improved in concealment and flexibility. The addition ratio is 0.05 wt% to 1.0 wt% in the polymer. More preferably, 0.1% by weight to 1.0% by weight, more preferably 0.1% by weight to 0.7% by weight, and most preferably 0.2% by weight to 0.7% by weight. %.

  When the addition rate is less than 0.05% by weight, the peeling effect between the embossing roll and the heat-bonding sheet is poor, and when it exceeds 1.0% by weight, there is an adverse effect such as single yarn breakage.

  The inorganic fine particles or lubricant may be added to both the core component and the sheath component when the die configuration is a core-sheath type, but it is sufficient to add the inorganic fine particles or lubricant to at least the sheath component. The effect can be demonstrated. Moreover, the nonwoven fabric which has still more functionality can be obtained by providing a water repellent, a softening agent, etc. to the sheet | seat after heat bonding.

  The biodegradable nonwoven fabric used in the present invention can also be efficiently produced by a method in which at least one pair of a conventional spunbond method and a melt blow method is combined in-line. In the case of the biodegradable long-fiber nonwoven fabric A, in order to obtain a nonwoven fabric having a fiber diameter of 8 to 15 μm and good quality, the biodegradable resin is heated and melted with an extruder, and the discharge hole diameter is 0. After discharging from a base of 20 to 0.60 mm and cooling, high speed at 2000 m / min to 5500 m / min, more preferably 2500 m / min to 5000 m / min, more preferably 4300 m / min to 5000 m / min with an ejector. Towing is preferable. When the diameter of the nozzle hole is less than 0.20 mm, defects due to hole clogging immediately after the beginning of discharge are likely to occur, and when the diameter is larger than 0.60 mm, a single yarn flow is generated due to the spinning draft being too high. There are problems such as. When the spinning speed is less than 2000 m / min, not only the physical property level is lowered, but also the opening property of the filament is deteriorated, and the spot weight as a sheet is also deteriorated. Further, when the spinning speed exceeds 5500 m / min, there is a problem that the spinnability of the spun filament becomes insufficient and the single yarn breakage increases.

  In order to support high speed spinning while maintaining good spinnability, the cooling condition of the filament discharged from the die is important, and the length (cooling length) from the die surface to the ejector inlet is 50 cm to 100 cm. More preferably, the thickness is 60 cm to 80 cm. When the cooling length exceeds 100 cm, there is a problem that the balance between the chimney air flow and the accompanying flow is difficult to be obtained, and the yarn is liable to be distorted, and the spinnability is deteriorated and the unevenness due to the yarn is also deteriorated.

  Moreover, as conditions of the melt blown nonwoven fabric B when laminating the spunbond nonwoven fabric A and the melt blown nonwoven fabric B in-line, the hot air temperature to be injected is preferably 220 ° C. to 250 ° C., and the hot air pressure is 0.02 Mpa to 0.3 Mpa. good. This is because when the hot air temperature is less than 220 ° C, the viscosity of the molten polymer becomes high and the stretchability is lacking and uniform stretching is not performed. When the hot air temperature is higher than 250 ° C, the die temperature is high. This is because the thermal decomposition of the polymer becomes severe and disadvantages occur. When the hot air pressure exceeds 0.3 Mpa, the web of the spunbond nonwoven fabric A collected and conveyed on the collection net is generated due to too much hot air to be jetted, so that the nonwoven fabric can be satisfactorily satisfied as a nonwoven fabric. Cannot be obtained. Further, when the hot air pressure is less than 0.02 MPa, sufficient traction force cannot be obtained and the fiber diameter becomes thick, so that the nonwoven fabric is hard and the quality is not good. In addition, the spun bond and melt blown spray distances from the point of quality, such as the ability to collect filaments and uneven spots, and the stability of the quality, in the case of spunbond, the distance of the collection net moving from the outlet of the ejector for towing In the case of 30 cm to 60 cm and melt blow, it is preferable that the distance from the filament jet base to the collection net is 10 cm to 30 cm.

  The nonwoven fabric according to the present invention can be easily manufactured by thermally bonding the web collected on the collection net as described above.

EXAMPLES Hereinafter, although this invention is concretely demonstrated based on an Example, this invention is not limited by these Examples. In addition, each characteristic value in the following Example is measured by the following method.
(1) Melting point (° C):
It measured using the DSC6200 type | mold measuring apparatus by Seiko Instruments. Under the conditions of a sample amount of 10 mg, a temperature range of 40 to 300 ° C., a heating rate of 20 ° C./min, and a measurement interval of 0.5 seconds, the temperature giving an extreme value in the obtained melting endotherm curve was measured for two samples, Their average was taken as the melting point.
(2) Fiber diameter (μm):
Ten small piece samples were randomly collected from the nonwoven fabric, taken with a scanning electron microscope at a cross-sectional photograph of 100 to 5000 times, and each of the spunbond nonwoven fabric layer and the melt blown nonwoven fabric layer from n = 10 (total of 100). The fiber diameter (μm) was measured, the average value of each was calculated, and the fractional part was rounded to the fiber diameter (μm).
(3) Product weight (g / m ² ):
After leaving the sample under standard conditions for 24 hours, four samples of 50 cm in the vertical direction and 50 cm in the horizontal direction were collected, the weight (g) of each sample was measured, and the average value of the obtained values was expressed in unit area (m ² ), And rounded off to the nearest decimal place to obtain the basis weight of the nonwoven fabric (g / m ² ).

The unit weight of each layer in the spunbond and meltblown nonwoven fabric is determined based on the discharge amount, sheet width, and collection net speed of each layer. Single layer basis weight of each layer = discharge amount (g / min) / {width (m) × speed (m / Min)}
Calculated by
(4) Bending softness (mm):
The bending resistance in the vertical direction was measured by JIS L1096, 6.19.1 A method (45 ° cantilever method).

That is, five samples of width direction (horizontal direction) 2 cm × length direction (longitudinal direction) 15 cm were taken from the sample, and the end piece of the test piece was placed on a horizontal table with one end having a 45-degree slope and a smooth surface. Is placed on the base line of the scale, and the test piece is gently slid in the direction of the slope. When the center point of one end of the test piece touches the slope, read the position of the other end on the scale and measure the front and back of the five pieces. The average value was defined as the bending resistance.
(5) Texture:
A sample having a width of 20 cm and a length of 20 cm was taken from the nonwoven fabric and evaluated by a monitor of five people. The sample was rubbed by hand, the flexibility of the nonwoven fabric was evaluated, judged according to the following criteria, and ranked according to the total score. The higher the total score, the more flexible the sample.

  3 points: The nonwoven fabric is soft and flexible.

  2 points: The feel of the nonwoven fabric is normal.

1 point: The touch of the nonwoven fabric is hard.
(6) Product quality:
A sample having a width of 100 cm and a length of 50 cm was taken from the nonwoven fabric, and visually judged as follows.

  ○: Good quality with no wrinkles or the like due to heat shrinkage during emboss bonding.

  Δ: Wrinkles are partially observed, but there is no problem in use.

X: There are many wrinkles and the quality is extremely poor.
(7) Water pressure resistance (mm)
It measured using the water pressure-resistant measuring apparatus according to JIS-L-1092. A sample cut to 160 mm × 160 mm is set in a measuring device, a level device containing distilled water is raised at a speed of 10 cm / min, and the water level of the manometer when one drop of water comes out from the nonwoven fabric surface is read. Ten samples were measured and the average value was taken as the water pressure resistance.
(8) Fluctuation rate of fiber diameter (CV%)
Based on the fiber diameter measurement result, the measured value of the melt blow part of the middle layer was calculated by the following formula.

(9) Fuzz Dyeing fastness test method for friction (friction tester type II) In accordance with JIS-L0849, six samples each having a width of 30 mm and a length of 220 mm were collected in the longitudinal and lateral directions of the nonwoven fabric. A 200 g load was applied to the nonwoven fabric, and the nonwoven fabric was measured 100 times in the longitudinal direction and 50 times in the lateral direction, and the surface condition of the friction surface was observed and determined as follows.

  ○: There is almost no fluffing on the surface, and it is recognized that there is no problem in use.

  Δ: Fluff on the surface, but no problem in use.

X: The surface has many fuzz and has a problem in use.
(10) Biodegradability:
Three nonwoven fabrics having a size of 20 cm × 20 cm were collected, embedded in about 10 cm of soil, and the shape change after being left for 6 months was visually evaluated.

Non-woven fabric with biodegradability: ○
Non-biodegradable non-woven fabric: ×
Examples 1-7
A polylactic acid resin having a weight average molecular weight of 150,000, a Q value (Mw / Mn) of 1.78 and a melting point of 170 ° C. is used for spunbond, and a weight average molecular weight is 96,000 for meltblowing. The polylactic acid resin having a Q value of 1.68 was separately dried at 100 ° C. for 24 hours using a vacuum dryer.

  Next, a spunbond facility having a rectangular die having a diameter of 0.3 mm and a number of holes per 1 m width of 3500 holes and a rectangular ejector, and having a diameter of 0.4 mm and a discharge hole having a pitch of 1 mm. A melt blow equipment and a spunbond equipment having a rectangular base having a diameter of 0.3 mm and a number of holes per 1 m width of 3500 holes and a rectangular ejector are arranged in series, and the front and back surfaces of the nonwoven fabric are spanned. An equipment capable of producing a melt-blown nonwoven fabric with a bonded nonwoven fabric as an intermediate layer was used. The temperature of the spunbond extruder located at the end of the collection net progression is 230 ° C, the spinning temperature is 235 ° C, the discharge rate is changed as shown in Table 1, and after spinning, the cooling temperature is 15 ° C. They were pulled at a high speed at a rectangular ejector pressure of 0.3 Mpa and a spinning speed of 4800 m / min, and collected on a moving net conveyor. Subsequently, the temperature of the melt blown extruder for forming the middle layer was set to 235 ° C., the die temperature was set to 235 ° C., and the discharge amount and hot air pressure were appropriately changed to adjust the fiber diameter and basis weight ratio of the melt blow layer as shown in Table 1. And laminated on a nonwoven web formed by a spunbond facility located at the end of the net traveling direction.

  Subsequently, a spunbond nonwoven web spun under the same conditions and method as the spunbond equipment at the end of the net traveling direction located in the front row of the net traveling direction is jetted onto the melt blown nonwoven web constituting the intermediate layer. Gathered. The laminated web of the obtained spunbond layer, meltblown layer, and spunbond web layer is flat on one side and uneven on one side, the area ratio of the convex surface is 18%, the embossing temperature is 140 ° C., and the embossing pressure is A nonwoven fabric was manufactured by thermocompression bonding at 50 kg / cm.

  The obtained non-woven fabric was free from shrink wrinkles due to thermal bonding, was of good quality, showed good results in bending resistance and texture, and was also satisfactory in water pressure resistance. Moreover, all had sufficient biodegradability.

  The evaluation results are shown in Table 1.

Examples 8-10
Using the non-woven fabric obtained in Example 3, manufactured by Mike Rex Co., Ltd., indentation ratios of 10%, 15%, and 20% by a micro creper (the sheet feeding speed was increased to 10%, 15%, and 20% of the discharge speed As a result, the texture was greatly softened and the bending resistance was greatly reduced, which was satisfactory as a medical hygiene material, packaging material and agricultural material.

  The evaluation results are shown in Table 2.

Comparative Examples 1-7
The same equipment and raw materials as in Example 1 were used, the spunbond and meltblown discharge rates were changed, and in meltblown, the hot air wind speed was changed to adjust the respective fiber diameters and basis weights, and they were collected on the net. Bond, meltblown, spunbond laminated web, one side is flat and uneven on one side, convex area ratio is 6%, 18% and 40%, embossing temperature 140 ° C, embossing pressure 50kg / cm Crimped.

  In Comparative Example 1, the weight ratio of the melt blown nonwoven fabric constituting the laminated nonwoven fabric is as high as 40%, the width shrinkage at the time of thermocompression bonding is large, wrinkles are generated around the ears, the quality is poor, the bending resistance is high, and the texture Was not good either.

  In Comparative Example 2, the melt blow ratio was small and the water pressure resistance was insufficient.

  In Comparative Example 3, since the nonwoven fabric basis weight was too high, the bending resistance was high and the texture was not good.

  In Comparative Example 4, the fiber diameter of the spunbond was large and the bending resistance was high, and the texture and water pressure resistance were not satisfactory.

  In Comparative Example 5, both the spunbond and the melt blown nonwoven fabric had high fiber diameters and high bending resistance, and both the texture and water pressure resistance were worse than those in Comparative Example 4.

  In Comparative Example 6, since the non-woven fabric had a high thermocompression bonding area of 40%, the bending resistance was extremely high, the texture was hard, and it could not be used as a medical hygiene material, packaging material or agricultural material.

  In Comparative Example 7, the thermocompression bonding area of the nonwoven fabric was as low as 6%, so that the thermocompression bonding was insufficient, and there were many fluffs on the surface, which could not be used as a medical hygiene material, packaging material or agricultural material.

  The above evaluation results are summarized in Table 3.

Claims (10)

Biodegradable filament nonwoven fabric A fiber diameter of a 8μm~15μm and weight per unit area is 6-10 g / m ² constituting the nonwoven fabric, the basis weight average fiber diameter of a 2μm~8μm is 2 to 6 g / m ^2. A non-woven fabric characterized by comprising a structure in which at least two types of non-woven fabric of biodegradable long-fiber non-woven fabric B, which is ² , are laminated. The nonwoven fabric according to claim 1, wherein the nonwoven fabric A is a spunbond nonwoven fabric and the nonwoven fabric B is a meltblown nonwoven fabric. The variation rate of the fiber diameter of the nonwoven fabric B constituting the laminated nonwoven fabric is 30 to 60%, and the weight ratio of the nonwoven fabric B in the laminated nonwoven fabric is 12 to 30%. 2. The nonwoven fabric according to 2. The said biodegradable nonwoven fabric A and B are partially thermocompression bonded, and the total area of a partial thermocompression bonding part is 8 to 30% of the whole, The any one of Claims 1-3 characterized by the above-mentioned. Non-woven fabric. The bending resistance (measurement in the vertical direction) measured by the JIS-L-1096A method (45 ° cantilever method) of the biodegradable nonwoven fabric is 30 to 65 mm. Non-woven fabric. The melting point of the polymer constituting the biodegradable nonwoven fabric A and the biodegradable nonwoven fabric B is substantially the same, or the melting point difference is within 50 ° C. The nonwoven fabric described. The nonwoven fabric constituting the biodegradable nonwoven fabric A and the biodegradable nonwoven fabric B is composed of polylactic acid or polybutylene succinate, or a combination thereof. The non-woven fabric according to crab. A medical hygiene material comprising the nonwoven fabric according to any one of claims 1 to 7. A packaging material comprising the nonwoven fabric according to any one of claims 1 to 7. An agricultural material comprising the nonwoven fabric according to any one of claims 1 to 7.