JP2005009063A - Polylactic acid filament nonwoven fabric and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid filament nonwoven fabric having good yarn-making productivity and openability, stably and easily carrying out a thermal bonding process with scarcely shrunk or the like, while having a heat-sealing property. <P>SOLUTION: This polylactic acid filament nonwoven fabric produced by a spun bond method comprising accumulating conjugated filaments comprising a (polymer A) obtained by blending an aliphatic copolyester comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid and a lactic acid polymer and a polylactic acid-based polymer (polymer B), wherein the polymers satisfy following melting characteristics, the polymer A forms at least a portion of the surface of filaments and the thermal adhesion of mutual filaments is carried out by melting or softening of at least a portion of the polymer A. (1) The melting point of the lactic acid polymer in polymer A and B is ≥150°C. (2) The melting point of the aliphatic copolyester is lower than that of the polymer B. (3) The aliphatic copolyester has a crystal melting point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polylactic acid long fiber nonwoven fabric having biodegradability and excellent mechanical properties and heat seal properties, and a method for producing the same.

  One of the functional long-fiber nonwoven fabrics is a long-fiber nonwoven fabric made of self-adhesive fibers. The long-fiber non-woven fabric made of self-adhesive fibers is formed by melting a part of the fibers by heating and bonding and integrating the fibers, and has heat seal characteristics.

  In recent years, synthetic fibers made from petroleum have a large calorific value during incineration, so it has been necessary to review them from the viewpoint of protecting the natural environment, and fibers made of aliphatic polyester that biodegrades in nature have been developed. Contributing to protection is expected. Among aliphatic polyesters, polylactic acid polymers are expected to be used in a wide range of fields because they have a relatively high melting point.

  Of the polylactic acid polymers, poly-L-lactic acid or poly-D-lactic acid is crystalline and has a high melting point of about 180 ° C., and L-lactic acid and D-lactic acid are copolymerized. The melting point of the copolymer (D, L-lactic acid copolymer) can be changed by appropriately selecting the copolymerization ratio. For example, when L-lactic acid is copolymerized with 1 mol% of D-lactic acid, the melting point is about 170 ° C., and when D-lactic acid is copolymerized with 5 mol%, the melting point is about 150 ° C. and D-lactic acid is copolymerized with 8 mol%. The melting point can be controlled such that the melting point is about 120 ° C. However, as the amount of copolymerization is increased, the crystallinity is lost accordingly. In such a D, L-lactic acid copolymer, a copolymer of more than 5 mol% becomes amorphous and tends to be inferior in thermal stability.

  When trying to obtain a self-adhesive long fiber nonwoven fabric using a polylactic acid-based polymer, a core-sheath type composite fiber in which poly-L-lactic acid is arranged in the core part and D, L-lactic acid copolymer is arranged in the sheath part It can be considered to be configured by Considering the heat processing stability during heat seal processing, it is preferable that the melting point difference between the core and the sheath is large, that is, it is preferable to provide the melting point difference of about 50 ° C. Therefore, the copolymer of the sheath has a melting point. It is considered preferable to select a low one (a copolymer at about 120 ° C.). Specific examples of such combinations include those disclosed in the examples of Patent Document 1.

  However, the D, L-lactic acid copolymer having a melting point of about 120 ° C. is an amorphous one in which D-lactic acid is copolymerized in an amount exceeding 5 mol%, so that the spunbond is pulled at a stretch at a high speed. In the method, since it does not crystallize sufficiently, troubles such as shrinkage in the heat bonding step after obtaining the web or fusion to the heat roll are likely to occur, and the obtained nonwoven fabric is inferior in heat resistance. Become.

  On the other hand, in consideration of the above problem, if a sheath having a D, L-lactic acid copolymer having a high melting point of about 150 ° C. is selected, the above problem can be solved, but the core portion can be used during heat sealing. Since the melting point difference between the sheath portion and the sheath portion is not large, the polymer in the core portion is affected by heat, so the heat seal strength is not improved, and it is not possible to obtain one having excellent heat seal properties.

  In addition, it is considered to be composed of core-sheath type composite long fiber in which an aliphatic polyester obtained from an aliphatic diol such as polyethylene succinate and polybutylene succinate and an aliphatic dicarboxylic acid is arranged in the core part and polylactic acid in the core part. It is done. However, since these aliphatic polyesters have a low glass transition temperature (Tg), the distance and time until the yarn discharged from the nozzle hole is pulled down is limited as in the spinning process of the spunbond method. In such a method, the cooling process with the cooling air does not sufficiently cool, and problems such as rubber elasticity and blocking occur.

Japanese Patent No. 3161245 Example

  The present invention has good spinning and opening properties, can be efficiently produced by a spunbond method, has little shrinkage during the heat bonding process, and stably and easily performs heat treatment. Furthermore, it is an object of the present invention to provide a polylactic acid-based long-fiber nonwoven fabric having excellent heat sealability.

  In order to achieve the above-mentioned problems, the present inventors have conducted intensive studies.

  First, polylactic acid having a high melting point is arranged in the core, and blended with an aliphatic polyester obtained from an aliphatic diol and an aliphatic dicarboxylic acid having a low melting point but poor cooling properties, and blending polylactic acid having excellent cooling properties. A polymer with improved cooling properties was placed in the sheath and an attempt was made to obtain a core-sheath type composite fiber by the spunbond method. However, the above-mentioned polymers constituting the blend are not compatible with each other and cannot increase the blend ratio of polylactic acid, so that the cooling property cannot be improved, and a nonwoven fabric is obtained by a spunbond method. I couldn't.

  As a result of intensive studies to increase the blend ratio of polylactic acid in the blend, the present inventors have selected a specific copolymer as the aliphatic polyester to be blended, so that it can be pulled at high speed by the spunbond method. The inventors have obtained the knowledge that the blend ratio is increased and the above-mentioned problems can be achieved, and the present invention has been achieved.

That is, the present invention relates to a polymer (polymer) obtained by blending an aliphatic polyester copolymer (a) having an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituents with a polylactic acid polymer. A nonwoven fabric obtained by depositing composite long fibers comprising a polymer A) and a polylactic acid polymer (polymer B) by a spunbond method, and the polymer satisfies the following melting characteristics (1) to (3) The polymer A forms at least a part of the fiber surface, and at least a part of the polymer A melts or softens, whereby the fibers are thermally bonded to each other to maintain the shape. The gist is a polylactic acid-based long fiber nonwoven fabric.
(1) The melting points of the polylactic acid polymers used for the polymer A and the polymer B are both 150 ° C. or higher.
(2) The melting point of the aliphatic polyester copolymer (a) is lower than the melting point of the polymer B.
(3) The aliphatic polyester copolymer (a) has a crystalline melting point.

  The present invention also relates to an aliphatic polyester copolymer (a) comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid, which satisfy the melting characteristics (1) to (3) above. A polymer obtained by blending a polylactic acid polymer (polymer A) and a polylactic acid polymer (polymer B) are separately melt-measured, and the polymer A is applied to the fiber surface from a composite spinneret. After discharging the yarn forming at least a part of the yarn, the discharged yarn is pulled and thinned by a suction device, and then deposited on the movable collection surface while being deposited to form a web, and then the web This is a gist of a method for producing a polylactic acid-based continuous fiber non-woven fabric, wherein the fibers are heat-bonded by heat-treating and melting or softening at least a part of the polymer A.

  The present invention relates to a blend (polymer A) of an aliphatic polyester copolymer (a) composed of an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid and a polylactic acid polymer, and a polylactic acid heavy polymer. It is a nonwoven fabric by a spunbond method in which composite long fibers made of a polymer (polymer B) are deposited. The polymer A forms at least a part of the fiber surface, and at least a part of the polymer A melts or softens so that the fibers are thermally bonded to each other to maintain the form.

  Since the melting points of the polylactic acid polymers used for the polymer A and the polymer B are both 150 ° C. or higher, the crystallinity is high and the thermal stability is obtained. Accordingly, the spinning property and the fiber opening property are good, and shrinkage or the like does not occur during the heat bonding process.

  In addition, since the polymer A which is an adhesive component is blended with the low melting point aliphatic polyester copolymer (a) having a crystalline melting point, this contributes as an adhesive component and has a crystalline melting point. Therefore, heat treatment and heat sealing can be performed stably and easily without paying close attention to heat treatment conditions.

  Therefore, according to the present invention, it is possible to provide a biodegradable long fiber nonwoven fabric excellent in mechanical properties and heat seal specification.

  The present invention relates to a polymer (polymer A) obtained by blending an aliphatic polyester copolymer (a) having an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituents with a polylactic acid polymer. ) And a polylactic acid polymer (polymer B) is a non-woven fabric formed by depositing by a spunbond method.

  First, the polylactic acid-type polymer used for the polymer A and the polymer B constituting the composite long fiber will be described.

  Examples of the polylactic acid polymer used in the present invention include poly-D-lactic acid, poly-L-lactic acid, a copolymer of D-lactic acid and L-lactic acid (D, L-lactic acid copolymer), and a melting point. Are those having a temperature of 150 ° C. or higher, or blends thereof. When the melting point of the polylactic acid polymer is 150 ° C. or higher, since it has high crystallinity, the cooling property during spinning becomes good, and a nonwoven fabric can be satisfactorily obtained by the spunbond method. Moreover, the shrinkage | contraction at the time of heat processing does not generate | occur | produce easily, heat processing can be performed stably, and the nonwoven fabric obtained is excellent in heat resistance.

  When a copolymer is used as the polylactic acid polymer, the copolymerization ratio of D-lactic acid and L-lactic acid is determined so that the melting point of the copolymer is 150 ° C. or higher. In the D, L-lactic acid copolymer, a copolymer having a copolymerization ratio (molar ratio) of 95 mol% or more and less than 100 mol% of either L-lactic acid or D-lactic acid may be used. When the copolymerization ratio is outside the above range, the melting point of the copolymer becomes less than 150 ° C. or becomes amorphous, and it is difficult to achieve the object of the present invention.

  The polylactic acid polymer used for the polymer A and the polylactic acid polymer used for the polymer B may be the same or different.

  Next, the aliphatic polyester copolymer (a) containing as constituent components an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid used for the polymer A will be described.

  Aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedi Methanol. These may be used alone or in combination. Of these, it is preferable to use 1,4-butanediol in consideration of the physical properties of the aliphatic polyester copolymer (a) to be obtained.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, suberic acid, dodecanedioic acid, and the like, and acid anhydrides that are derivatives thereof may be used. Of these, it is preferable to use succinic acid or succinic anhydride, or a combination thereof with adipic acid in consideration of the physical properties of the resulting aliphatic polyester copolymer (a).

  Examples of the aliphatic hydroxycarboxylic acid include lactic acid, glycolic acid, 2-hydroxy-n-butyric acid, 2-hydroxycaproic acid, 2-hydroxyisocaproic acid, 2-hydroxy-3,3-dimethylbutyric acid, and 2-hydroxy-3. -Methyl lactic acid, leucine acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, methyl lactic acid, caprolactone, valerolactone and the like. Of these, lactic acid is preferably used.

  The aliphatic polyester copolymer (a) is obtained by polycondensation of the above-mentioned aliphatic diol, aliphatic dicarboxylic acid and aliphatic hydroxycarboxylic acid. Even if it is a block copolymer, it is a random copolymer. It may be.

  As the aliphatic polyester copolymer (a) used in the present invention, for example, an aliphatic polyester copolymer described in Japanese Patent No. 3418070 is preferably used. The aliphatic polyester copolymer described in Japanese Patent No. 3418070 is composed of an aliphatic dicarboxylic acid, an aliphatic diol, and an aliphatic hydroxycarboxylic acid, and at least a part of the aliphatic hydroxycarboxylic acid is lactic acid. It is.

  In the aliphatic polyester copolymer (a), the melting point is lower than the melting point of the polylactic acid polymer as the polymer B and has a crystalline melting point. When the melting point is lower than that of the polymer B, it functions as an adhesive component (binder), and when it has a crystalline melting point, troubles are less likely to occur in the thermal bonding step. Having a crystalline melting point has a clear melting point peak in the DSC melting endothermic curve in differential scanning calorimetry. The melting point difference between the aliphatic polyester copolymer (a) and the polymer B is preferably 50 ° C. or higher in consideration of thermal processing stability and heat seal characteristics.

  Therefore, in the present invention, the aliphatic diol is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, the aliphatic hydroxycarboxylic acid is lactic acid, and the melting point of the polylactic acid polymer that is the polymer B Also, an aliphatic polyester copolymer (a) having a crystalline melting point lower by 50 ° C. or more can be preferably used.

  The polylactic acid-based polymer to be blended is obtained by copolymerizing an aliphatic hydroxycarboxylic acid as a component constituting the aliphatic polyester copolymer (a) (preferably, the aliphatic hydroxycarboxylic acid is lactic acid). Compatibility with the coalescence is improved, and the blend ratio of both can be improved. As a result, the heat seal characteristics of the long-fiber nonwoven fabric of the present invention are improved, and the cooling property is improved. Therefore, the yarn can withstand the stress caused by high-speed spinning, and a spunbonded nonwoven fabric can be obtained satisfactorily. The blend ratio (mass ratio) in the polymer A is preferably aliphatic polyester copolymer (a) / polylactic acid-based polymer = 5/95 to 30/70. When the blend ratio of the aliphatic polyester copolymer (a) is less than 5% by mass, the component that contributes as a thermal bonding component is reduced, so that the adhesiveness tends to be inferior, and sufficient mechanical strength is obtained. It is difficult to obtain heat sealability. On the other hand, when the blend ratio of the aliphatic polyester copolymer (a) exceeds 30% by mass, when a long fiber nonwoven fabric is obtained by the spunbond method, the cooling property at the time of spinning is inferior, and the spun and stretched yarns are It tends to adhere and cannot be opened.

  The melt flow rate (hereinafter abbreviated as MFR) of polymer A and polymer B constituting the composite long fiber is preferably 20 g / 10 min to 80 g / 10 min. When the form of the composite long fiber is a core-sheath type, the melt flow rate value of the aliphatic polyester copolymer (a) is MFRx, and the melt flow rate value of the polylactic acid polymer in the polymer A is Assuming that MFRy, these relationships are preferably MFRx ≧ MFRy, and MFRy is preferably 30 to 50 g / 10 min. When MFRx and MFRy are in the above relationship, aliphatic polyester copolymer (a) component having low viscosity on the fiber surface of the sheath component (polymer A) during melt spinning (large MFR value) and good fluidity In the sheath component of the cross section of the fiber that has been cooled and solidified, the blend layer rich in the aliphatic polyester copolymer (a) on the front side (fiber surface side) and the layer rich in polylactic acid inside it Are formed. That is, the outermost layer of the fiber is a blend layer rich in the aliphatic polyester copolymer (a) on the sheath surface, the polylactic acid rich layer inside the sheath, and the core is a polylactic acid polymer. As a result, the composite continuous fiber nonwoven fabric formed from the core-sheath composite fiber is excellent in heat sealability. Note that the boundaries between these layers need not be clear.

  Here, MFR is a value measured at a temperature of 210 ° C. and a load of 20.2 N (2160 gf) according to the method described in ASTM-D-1238.

  Various additives such as a matting agent, a pigment, and a crystal nucleating agent may be added to the polymer used in the present invention as necessary, as long as the effects of the present invention are not impaired. In particular, the addition of a crystal nucleating agent such as talc, titanium oxide, calcium carbonate, magnesium carbonate or the like is performed in order to prevent fusion (blocking) between yarns in the spinning / cooling step. It is useful when used in the mass% range.

  When a pigment is added to the polymer used in the present invention, it may be added to both the polymer A and the polymer B. However, in consideration of oriented crystallization in the spinning process, it may be added to one of the components. preferable. This is because when the pigment is added to the polymer, orientation crystallization is difficult to proceed in the spinning process. More preferably, a pigment is added to the polymer A that functions as an adhesive component, and the oriented crystallization is enhanced without adding it to the polymer B serving as a skeleton, and the sheath component of the resulting composite long fiber (polymer A) In the core component (polymer B) as a skeleton, the orientation crystallization is increased and the strength as the fiber is increased by suppressing the orientation crystallization to improve the adhesion strength at the time of thermal bonding. It is preferable to improve the strength of the long-fiber nonwoven fabric by improving both the adhesive strength and the fiber strength. Moreover, the pigment to add is good in it being 0.5-2 mass% per component.

  In the composite long fiber in the present invention, the polymer A forms at least a part of the fiber surface. As a cross-sectional form of such a composite long fiber, a side-by-side type composite cross section in which a polymer A and a polymer B are bonded together, a core in which the polymer B forms a core and the polymer A forms a sheath Examples include a sheath-type composite cross section, a split-type composite cross section in which the polymer A and the polymer B are alternately present on the fiber surface, and a multileaf composite cross section. Among these, considering the role of the polymer A as a thermal adhesive component, the core-sheath composite cross section is preferable.

  When the cross-sectional form of the composite long fiber is a core-sheath composite cross section, the composite ratio (mass ratio) of the core part and the sheath part is preferably core part / sheath part = 5/1 to 1/1. When the ratio of the core exceeds 5/1, the ratio of the sheath is decreased, the thermal bonding performance is insufficient, the shape retention and mechanical performance of the long-fiber nonwoven fabric tend to be inferior, and sufficient heat sealing is achieved. It is difficult to get sex. On the other hand, when the ratio of the core portion is less than 1/1, in the production process, the spinning yarn tends to be inferior in cooling property, the spinning property and the fiber opening property are poor, and the spun and drawn yarns are easily adhered to each other. .

  Although the single yarn fineness of the composite continuous fiber in this invention is not specifically limited, What is necessary is just about 0.5-11 decitex. If the single yarn fineness is less than 0.5 dtex, yarn breakage frequently occurs in the spinning / drawing process, and the operability deteriorates. On the other hand, when the single yarn fineness exceeds 11 dtex, the spinning yarn is inferior in cooling property, and the yarns are easily adhered to each other.

  The present invention is a non-woven fabric by the spunbond method in which the composite long fibers described above are deposited, and at least a part of the polymer A is melted or softened so that the fibers are thermally bonded to each other to maintain the shape. Here, as a form of thermal bonding, even if it is heat-bonded via a polymer A formed by melting or softening at a contact point between fibers, it can be partially passed by passing through a heat embossing device. A thermocompression bonding part and a non-thermocompression bonding part may be formed, and in the thermocompression bonding part, the polymer A may be melted or softened and retained in the form of a nonwoven fabric. In the present invention, the latter form of thermal bonding is preferred.

The basis weight of the long-fiber nonwoven fabric of the present invention is not particularly limited and may be appropriately selected depending on the application, but is preferably about 10 to 300 g / m ² . If the basis weight is less than 10 g / m ² , the formation and mechanical strength are inferior and impractical. On the other hand, when the basis weight exceeds 300 g / m ² , it is disadvantageous in terms of cost and tends to be inferior in heat sealability.

  Next, the manufacturing method of the polylactic acid-type long fiber nonwoven fabric of this invention is demonstrated. The polylactic acid long fiber nonwoven fabric in the present invention can be efficiently produced by a so-called spunbond method.

  An aliphatic polyester copolymer (a) and a polylactic acid polymer used for the polymer A are prepared. As a method of blending the aliphatic polyester copolymer (a) and the polylactic acid polymer, a polylactic acid polymer chip and an aliphatic polyester copolymer chip are prepared, the chips are weighed and mixed, Either a method of performing melt spinning while melt-mixing in a rudder, or a method of using a blended chip obtained by melting and blending a predetermined amount of both in advance may be used. Further, one chip may be further mixed with the blend chip.

  The polymer A and the separately prepared polymer B were separately melt-metered, and the polymer A was discharged from a composite spinneret so that a fiber cross section forming at least part of the fiber surface was obtained. The spun yarn is cooled using a conventionally known cooling device such as a horizontal spray or an annular spray, and then pulled and thinned using a suction device.

  The pulling speed at this time is preferably set to 4000 to 6000 m / min, and more preferably 4500 to 5500 m / min. When the pulling speed is less than 4000 m / min, the molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the obtained long fiber nonwoven fabric tends to be inferior. On the other hand, if the pulling speed is too high, the spinning stability tends to be poor.

  The drawn and thinned long fibers are deposited on a movable collection surface such as a conveyor made of a screen while opening with a known opening device to form a web.

  Subsequently, the obtained web is subjected to heat treatment, and at least a part of the polymer A is melted or softened, whereby the fibers are thermally bonded to obtain the polylactic acid-based long fiber nonwoven fabric of the present invention.

  Examples of the heat treatment method include a method of blowing hot air, a method of passing through a hot embossing device, and the like. In the point which is excellent in both a softness | flexibility and mechanical strength, it is preferable to pass through a hot embossing apparatus.

  What is necessary is just to set the preset temperature at the time of heat processing to the temperature which the aliphatic polyester copolymer of the polymer A melt | dissolves or softens, and it selects suitably according to processing time etc.

  For example, when passing through a hot embossing device, the surface temperature of the roll is preferably set to a temperature lower by 10 to 50 ° C. than the melting point of the aliphatic polyester copolymer (a). When the temperature is set to a temperature lower than 50 ° C. lower than the melting point of the aliphatic polyester copolymer, the aliphatic polyester copolymer does not sufficiently melt or soften, so that the adhesive function is inferior, and the mechanical performance of the long fiber nonwoven fabric is low. Inferior and prone to fluff. On the other hand, when the temperature is set higher than the temperature lower by 10 ° C. than the melting point of the aliphatic polyester copolymer, the molten polymer is fixed to the roll, and the operability is remarkably impaired.

Hereinafter, the present invention will be described specifically by way of examples. In addition, this invention is not limited only to these Examples. The physical property values and the like in the following examples and comparative examples were determined as follows.
(1) Melting point (° C.) of polymer; melting endothermic curve obtained by using a differential scanning calorimeter DSC-7 manufactured by Perkin Elma Co., Ltd. with a sample mass of 5 mg and a heating rate of 10 ° C./min. The temperature giving the extreme value of the endothermic peak was defined as the melting point Tm (° C.).

(2) Weight per unit area (g / m ² ): 10 pieces each of 10 cm long × 10 cm wide sample pieces were prepared from the nonwoven fabric in the standard state, and after reaching the equilibrium moisture, the mass (g) of each sample piece was weighed. The average value of the obtained values was converted per unit area to obtain the basis weight of the nonwoven fabric (g / m ² ).

(3) Tensile strength (N / 5 cm width) and elongation at break (%): 10 sample pieces each having a sample length of 20 cm and a sample width of 5 cm were prepared, and a constant speed extension type tensile tester (Orientec) was used for each sample. Tensilon UTM-4-1-100 manufactured by Komatsu Ltd. was used to measure the load value (N / 5 cm width) at the time of cutting by stretching at a gripping interval of 10 cm and a tensile speed of 20 cm / min. It was set as strong (N / 5 cm width). The elongation at break was defined as the average elongation (%) at the time of cutting obtained under the above conditions.

In the present invention, the value obtained by dividing the tensile strength by the basis weight is preferably 1.96 N / 5 cm width / (g / m ² ) or more in the machine direction (MD direction). Those having a width of less than 1.96 N / 5 cm width / (g / m ² ) are not practical because it is difficult to say that they have excellent mechanical strength. Further, the breaking elongation is preferably 20% or more in both the vertical direction (MD direction) and the horizontal direction (CD direction). A material having a breaking elongation of less than 20% is not practical because it breaks as soon as a load is applied when the nonwoven fabric is applied to various uses. The upper limit of the elongation at break may be about 50%.

Example 1
As polymer A, melting point 155 ° C., MFR 40 g / 10 min D, L-lactic acid lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 95.5 / 4.5 mol%), melting point 110 ° C. MFR 40 g / 10 min 1,4-butanediol, succinic acid and aliphatic polyester copolymer (a) consisting of lactic acid and D, L-lactic acid copolymer / aliphatic polyester copolymer by mass ratio (A) A polymer obtained by melt blending so as to be 80/20 and blending both was prepared.

  On the other hand, as a polymer B, a melting point of 168 ° C., a D of MFR of 70 g / 10 min, and an L-lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 98.6 / 1.4 mol%) were prepared.

  Extruder type extrusion after individual melt-weighing so that the core part / sheath part = 2/1 (mass ratio) so that the polymer B is arranged in the core part and the polymer A in the sheath part It was melted at a spinning temperature of 210 ° C. using a machine, and melt-spun under a single hole discharge rate of 1.38 g / min so as to have a core-sheath composite cross section.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 4500 m / min with an air-soccer provided below the spinneret and opened using a known fiber opening device. The web was obtained by collecting and depositing on a moving screen conveyor. The openability was good, and the single yarn fineness of the deposited composite continuous fibers was 3.0 dtex.

Subsequently, the obtained web was partially thermocompression-bonded through an embossing device (roll surface temperature 95 ° C.) composed of an embossing roll and a flat roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 50 g / m ² . . In addition, as the embossing roll, a circular pattern having an individual area of 0.6 mm ² was engraved so that the crimping point density was 20 points / cm ² and the crimping area ratio was 12%.

  The resulting polylactic acid-based long fiber nonwoven fabric has a tensile strength in the machine direction (MD) of 130 N / 5 cm, a transverse direction (CD) of 54 N / 5 cm, and an elongation at break of 27% in the machine direction (MD). CD) was 38%.

Example 2
In Example 1, the blend ratio in the polymer A was melt-blended so that the D, L-lactic acid copolymer / aliphatic polyester copolymer (a) = 90/10, and the core and sheath The polylactic acid long fiber nonwoven fabric of Example 2 was obtained in the same manner as in Example 1 except that the composite ratio was 1/1 and the traction speed was 5000 m / min.

  Tensile strength of the obtained polylactic acid-based long fiber nonwoven fabric is longitudinal (MD) 118 N / 5 cm width, transverse direction (CD) 20 N / 5 cm width, elongation at break is 20% longitudinal (MD), transverse direction ( CD) 29%.

Examples 3 and 4
In Example 1, polylactic acid was obtained in the same manner as in Example 1 except that the basis weight of the long-fiber nonwoven fabric was 20 g / m ² (Example 3) and the basis weight was 100 g / m ² (Example 4). A long fiber nonwoven fabric was obtained.

  The tensile strength of the obtained polylactic acid-based long fiber nonwoven fabric of Example 3 is machine direction (MD) 42 N / 5 cm width, transverse direction (CD) 15 N / 5 cm width, breaking elongation is machine direction (MD) 24%. The transverse direction (CD) was 34%.

  The resulting polylactic acid-based long-fiber nonwoven fabric of Example 4 has a tensile strength in the machine direction (MD) of 220 N / 5 cm, a transverse direction (CD) of 58 N / 5 cm, and a breaking elongation of 20% in the machine direction (MD). The lateral direction (CD) was 23%.

Example 5
In Example 1, as the polymer B, an MFR of 20 g / 10 min. D, an L-lactic acid copolymer was used, a single hole discharge rate of 3.9 g / min, a pulling speed of 5000 m / min, a single yarn A polylactic acid long fiber nonwoven fabric was obtained in the same manner as in Example 1 except that the fineness was 7.7 dtex.

  Tensile strength of the obtained polylactic acid-based long fiber nonwoven fabric is longitudinal direction (MD) 105 N / 5 cm width, transverse direction (CD) 32 N / 5 cm width, breaking elongation is longitudinal direction (MD) 20%, transverse direction ( CD) 21%.

Example 6
Melting point 155 ° C., MFR 40 g / 10 min D, L-lactic acid lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 95.5 / 4.5 mol%), melting point 110 ° C., MFR 40 g / 10 min 1,4-butanediol, succinic acid, and lactic acid copolymer (a) (trade name “GSPla” manufactured by Mitsubishi Chemical Corporation) with D, L-lactic acid copolymer / The polymer (P1) which melt-blended so that it might become an aliphatic polyester copolymer (a) = 80/20, and both blended was prepared.

Moreover, 20 masses of talc is added to 80 mass parts of melting point 155 ° C., D, L-lactic acid lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 95.5 / 4.5 mol%) of MFR 40 g / 10 min. Part master batch (M1), melting point 155 ° C., MFR 40 g / 10 min D, L-lactic acid lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 95.5 / 4.5 mol%) ) A master batch (M2) containing 76.7 parts by mass of the following pigments (1) to (3) was prepared.
(1) Yellow pigment 14.7 parts by mass (2) Red pigment 4.8 parts by mass (3) Carbon black 3.8 parts by mass The talc content in the polymer A is 1.1% by mass. Further, the polymer A was used by blending P1, M1, and M2 so that the total content of pigments in the polymer A was 1.7% by mass.
Meanwhile, a D, L-lactic acid copolymer (copolymerization ratio L-lactic acid / D-lactic acid = 98.6 / 1.4 mol%) having a melting point of 168 ° C. and MFR of 70 g / 10 min was prepared. The D-lactic acid copolymer and M1 were blended so that the content of talc in the polymer B was 1.5% by mass, and this was used as the polymer B.

  Extruder type extrusion after individual melt-weighing so that the core part / sheath part = 2/1 (mass ratio) so that the polymer B is arranged in the core part and the polymer A in the sheath part The melt was melted at a spinning temperature of 210 ° C. using a machine, and melt-spun under a single hole discharge rate of 1.38 g / min so as to have a core-sheath composite cross section.

  After cooling the spun yarn with a known cooling device, it is subsequently pulverized at a traction speed of 4500 m / min with an air-soccer provided below the spinneret and opened using a known fiber opening device. The web was obtained by collecting and depositing on a moving screen conveyor. The openability was good, and the single yarn fineness of the deposited composite continuous fibers was 3.0 dtex.

Subsequently, the obtained web was partially thermocompression-bonded through an embossing device (roll surface temperature 95 ° C.) composed of an embossing roll and a flat roll to obtain a polylactic acid-based long fiber nonwoven fabric having a basis weight of 50 g / m ² . . In addition, as the embossing roll, a circular pattern having an individual area of 0.6 mm ² was engraved so that the crimping point density was 20 points / cm ² and the crimping area ratio was 12%.

  The resulting polylactic acid-based long-fiber nonwoven fabric has tensile strength of machine direction (MD) 129 N / 5 cm width, transverse direction (CD) 44 N / 5 cm width, elongation at break of machine direction (MD) 28%, transverse direction ( CD) was 38%.

Comparative Example In Example 1, instead of the blended polymer used as the polymer A, an aliphatic polyester composed of 1,4-butanediol having a melting point of 110 ° C. and MFR of 20 g / min and succinic acid (Showa Denko Co., Ltd.) The product was melt-spun so as to have a core-sheath type composite cross section in the same manner as in Example 1 except that the product name “Bionore”) was used. The spun yarn is not sufficiently cooled in the cooling process, the yarns are in close contact with each other, and cannot be pulled by the air soccer provided below the spinneret, and a nonwoven fabric obtained by the spunbond method can be obtained. There wasn't.

  About the obtained polylactic-acid type | system | group long-fiber nonwoven fabric of Examples 1-5, it evaluated by the following method about heat seal property and biodegradability. In any of the nonwoven fabrics, the heat sealability was good and the biodegradability was good.

(Heat sealability)
Using a seal tester, set the processing conditions (temperature 130 ° C., processing time 2 seconds, processing pressure 19.6 N / cm ² ), seal the two non-woven fabrics on top of each other, and peel the sealing part by hand. The peeled state was judged by the following three-level evaluation.
◯: Not peeled and sufficiently sealed Δ: Sealed portion is easily formed although it is formed into a film X: Almost not sealed Or although a seal part turns into a film, shrinkage | contraction of a sheet | seat occurs and dimensional stability is bad.

(Biodegradation performance)
A non-woven fabric is embedded in an aged compost maintained at about 58 ° C. and observed after 3 months. If the non-woven fabric does not retain its form, or even if it retains its form, the tensile strength is the strength before embedding. The biodegradation performance was evaluated as good when the initial value was reduced to 50% or less. On the other hand, when the strength exceeded 50% of the initial strength value before embedding, the biodegradation performance was evaluated as poor.

Claims (5)

A polymer (polymer A) obtained by blending an aliphatic polyester copolymer (a) and a polylactic acid-based polymer comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid as constituents; A nonwoven fabric obtained by depositing composite long fibers composed of a lactic acid-based polymer (polymer B) by a spunbond method, and the polymer satisfies the following melting characteristics (1) to (3), A polylactic acid-based long fiber characterized in that the coalescence A forms at least a part of the fiber surface, and at least a part of the polymer A melts or softens so that the fibers are thermally bonded to each other to maintain the shape. Non-woven fabric.
(1) The melting points of the polylactic acid polymers used for the polymer A and the polymer B are both 150 ° C. or higher.
(2) The melting point of the aliphatic polyester copolymer (a) is lower than the melting point of the polymer B.
(3) The aliphatic polyester copolymer (a) has a crystalline melting point. The aliphatic diol composing the aliphatic polyester copolymer (a) is 1,4-butanediol, the aliphatic dicarboxylic acid is succinic acid, the aliphatic hydroxycarboxylic acid is lactic acid, and the aliphatic polyester copolymer The polylactic acid long fiber nonwoven fabric according to claim 1, wherein the melting point of the polymer (a) is lower than the melting point of the polymer B by 50 ° C or more. The blend ratio (mass ratio) of the polymer A is aliphatic polyester copolymer (a) / polylactic acid polymer = 5/95 to 30/70. The polylactic acid-based long fiber nonwoven fabric according to item 1. The polylactic acid polymer used for the polymer A and the polymer B is a copolymer of D-lactic acid and L-lactic acid, and the copolymerization ratio (molar ratio) of either D-lactic acid or L-lactic acid. The polylactic acid-based long-fiber nonwoven fabric according to any one of claims 1 to 3, wherein is 95 mol% or more and less than 100 mol%. An aliphatic polyester copolymer (a) comprising an aliphatic diol, an aliphatic dicarboxylic acid and an aliphatic hydroxycarboxylic acid, which satisfy the following melting characteristics (1) to (3), and a polylactic acid-based polymer; A polymer (polymer A) and a polylactic acid polymer (polymer B) blended together are melt-metered separately, and the polymer A forms at least part of the fiber surface from the composite spinneret. After discharging the yarn to be discharged, the discharged yarn is pulled and thinned by a suction device, and then deposited on the movable collection surface while being deposited to form a web, and then the web is heat-treated to form a polymer. A method for producing a polylactic acid-based long-fiber nonwoven fabric, wherein fibers are thermally bonded by melting or softening at least a part of A.
(1) The melting points of the polylactic acid polymers used for the polymer A and the polymer B are both 150 ° C. or higher.
(2) The melting point of the aliphatic polyester copolymer (a) is lower than the melting point of the polymer B.
(3) The aliphatic polyester copolymer (a) has a crystalline melting point.