JP2006057197A - Polylactic acid-based nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polylactic acid-based nonwoven fabric which has good thermal moldability and heat resistance. <P>SOLUTION: This polylactic acid-based nonwoven fabric is characterized by laminating a filament nonwoven web layer formed from a polylactic acid-based polymer to a filament nonwoven web layer formed from an aromatic polyester-based polymer and then integrating the laminate by the mutual three-dimensional interlacement of the constituting filaments, and having a polylactic acid-based polymer melting point of ≥150°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polylactic acid-based nonwoven fabric, and particularly to a polylactic acid-based nonwoven fabric made of a plant-derived polymer having excellent thermoformability.

  In recent years, synthetic fibers using petroleum as a raw material have a large amount of heat generated during incineration, and therefore need to be reviewed from the viewpoint of protecting the natural environment. In contrast, fibers made of aliphatic polyester that biodegrades in nature have been developed and are expected to contribute to environmental protection. 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. In addition, polylactic acid polymers have the best balance of mechanical properties, heat resistance, and cost among biodegradable polymers. And development of the fiber using this is performed at a rapid pitch.

  However, the most promising polylactic acid polymer also has a problem of poor high-temperature mechanical properties. Here, poor high temperature mechanical properties indicate that the polymer rapidly softens when the glass transition temperature (Tg) of the polylactic acid polymer exceeds 60 ° C. Actually, when a tensile test of a long-fiber non-woven fabric made of a polylactic acid polymer is performed at a different temperature, it has been found that the strength of the long-fiber non-woven fabric rapidly decreases at 70 ° C. or higher.

  A long-fiber nonwoven fabric made of a polylactic acid-based polymer is inferior in mechanical properties at high temperatures as described above, so there is no problem when used in a normal atmosphere, but deformation and sag occur in a high-temperature atmosphere. For this reason, for example, it is unsuitable for the interior material for motor vehicles exposed to the sun. In addition, for example, when a polylactic acid-based long fiber nonwoven fabric is used for a thermoforming carpet, when it is thermoformed at a molding temperature such as 130 ° C. or 140 ° C., the nonwoven fabric has low strength and elongation at high temperatures. However, there is a problem that the carpet base fabric is torn at the portion where the deep drawing is performed.

  In order to compensate for the disadvantages of the above polylactic acid polymer, (1) a method of blending polyethylene terephthalate copolymerized with alkylene diol or bisphenol A derivative with polylactic acid, (2) polyethylene terephthalate copolymerized with long chain carboxylic acid Have been proposed, such as a method of blending lactic acid with polylactic acid, and (3) a method of utilizing an oriented crystallization structure by high-speed spinning.

Among these, a method using an oriented crystallization structure by high speed spinning will be described below. For example, homopoly L lactic acid having a weight average molecular weight of 100,000 to 300,000 is discharged from the die at a spinning temperature of 210 to 250 ° C., and the yarn is cooled and solidified by cooling air. Then, the oil agent for fibers is applied, taken up at a high speed, and wound up as it is. At this time, the high-speed take-up speed is determined so that the crystal size in the (200) plane direction of the wound polylactic acid fiber is 6 nm or more. Then, the polylactic acid fiber oriented and crystallized by this high-speed spinning is further stretched at a stretching temperature of 100 ° C. or higher and is heat-set (Patent Document 1).
JP 2003-41433 A

  An object of the present invention is to provide a polylactic acid-based nonwoven fabric that has good thermoformability and excellent heat resistance.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a laminated nonwoven fabric composed of a nonwoven web layer made of a polylactic acid polymer and a nonwoven web layer made of an aromatic polyester polymer, The inventors have found that excellent heat resistance and thermoformability can be imparted, and reached the present invention.

  That is, the present invention has the following configuration.

  (1) A long-fiber non-woven web layer formed of a polylactic acid-based polymer and a long-fiber non-woven web layer formed of an aromatic polyester-based polymer are laminated and the tertiary of constituent fibers A polylactic acid-based non-woven fabric, which is integrated by original entanglement and has a melting point of 150 ° C. or higher.

  (2) A polylactic acid-based nonwoven fabric characterized in that, in the above, the aromatic polyester-based polymer is one of polyethylene terephthalate and a copolymer mainly composed of the polyethylene terephthalate.

  (3) It is formed of the above polylactic acid-based nonwoven fabric, the maximum strength at 130 ° C. is 50 N / 5 cm width or more in both the vertical and horizontal directions, and the elongation at break at 130 ° C. is the vertical and horizontal directions. Both are 50% or more of the polylactic acid type nonwoven fabric for thermoforming characterized by the above-mentioned.

  (4) A method for producing the polylactic acid-based non-woven fabric or the polylactic acid-based non-woven fabric for thermoforming, comprising a long-fiber non-woven web layer formed of a polylactic acid-based polymer, and an aromatic polyester type Both nonwoven webs are laminated with a long fiber nonwoven web layer formed of a polymer, passed through a needle from the long fiber nonwoven web layer formed of an aromatic polyester polymer, and needle punched. A method for producing a non-woven fabric, wherein the constituent fibers of the layers are entangled and integrated.

  The polylactic acid-based non-woven fabric of the present invention is a composite long-fiber non-woven fabric composed of a laminated non-woven fabric of a long-fiber non-woven web layer made of a polylactic acid-based polymer and a long-fiber non-woven web layer made of an aromatic polyester-based polymer. It consists of The polylactic acid-based nonwoven fabric of the present invention has a melting point of a polylactic acid-based polymer of 150 ° C. or higher, a long-fiber nonwoven web layer composed of a polylactic acid-based polymer, and a long-fiber nonwoven fabric composed of an aromatic polyester-based polymer. Since the constituent fibers with the web layer are laminated and integrated by three-dimensional entanglement, good heat resistance is exhibited and, therefore, thermoformability in a high temperature atmosphere is good. In addition, since the thermoformability at high temperatures is good, it can be expected to be suitably used for applications requiring thermoformability such as carpet base fabrics for automobiles without greatly changing the conventional material design. .

  The polylactic acid nonwoven fabric of the present invention is composed of a laminated nonwoven fabric of a long fiber nonwoven web layer made of a polylactic acid polymer and a long fiber nonwoven web layer made of an aromatic polyester polymer. It is preferably used as a base fabric for lactic acid-based thermoformed carpets. In that case, because it has high strength and specific elongation even at high temperatures, it is difficult to break, exhibits sufficient elongation when thermoforming after tufting, and molding breaks while following the mold It can be expected to produce an effect that hardly occurs.

  In the polylactic acid-based nonwoven fabric of the present invention, a long fiber nonwoven web layer formed of a polylactic acid polymer and a long fiber nonwoven web layer formed of an aromatic polyester polymer are laminated and integrated. It is composed of a long fiber nonwoven fabric. Such a laminated structure has a non-woven web layer formed of an aromatic polyester polymer while exhibiting a predetermined biodegradability by the non-woven web layer formed of a polylactic acid polymer. This is because heat resistance, that is, mechanical properties at a high temperature are maintained and good thermoformability is exhibited.

First, the polylactic acid polymer 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, and a copolymer of D-lactic acid and hydroxycarboxylic acid. And a polymer selected from the group consisting of a polymer, a copolymer of L-lactic acid and hydroxycarboxylic acid, and a copolymer of D-lactic acid, L-lactic acid and hydroxycarboxylic acid, or a blend thereof. It is done. Examples of the hydroxycarboxylic acid for copolymerizing the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, etc. Hydroxycaproic acid and glycolic acid are preferable from the viewpoint of decomposition performance and cost reduction.

  In the present invention, a polylactic acid polymer having a melting point of 150 ° C. or higher or a blend of polymers having a melting point of 150 ° C. or higher is used. When the melting point of the polylactic acid-based polymer is 150 ° C. or higher, it has high crystallinity, so that it does not easily shrink during heat treatment, and the heat treatment can be performed stably. It becomes possible to obtain the nonwoven fabric excellent in heat resistance which is the object of the invention. On the contrary, if the melting point is lower than 150 ° C., it is difficult to obtain a nonwoven fabric excellent in heat resistance which is the object of the present invention.

  The melting point of poly-L-lactic acid and poly-D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C. When a copolymer is used as the polylactic acid polymer instead of a homopolymer, the copolymerization ratio of the monomer components is determined so that the melting point of the copolymer is 150 ° C. or higher. In the case of a copolymer of L-lactic acid and D-lactic acid, the copolymerization ratio of L-lactic acid and D-lactic acid is a molar ratio of (L-lactic acid) / (D-lactic acid) = 5/95. ˜0 / 100 or (L-lactic acid) / (D-lactic acid) = 95/5 to 100/0. When the copolymerization ratio is out of the above range, the melting point of the copolymer becomes less than 150 ° C., the amorphousness becomes high, the heat resistance is lowered, and the object of the present invention cannot be achieved.

  Examples of the aromatic polyester polymer used in the present invention include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate and the like, and copolymers, blends, alloys and the like based on these. The reason for using the aromatic polyester polymer is that the crystallinity of the resulting fiber is high and the heat resistance is excellent because of the high crystallinity. Especially, since it is excellent in productivity and high temperature physical property, a polyethylene terephthalate or a copolymer which has this as a main component is used suitably. In the case of a copolymer mainly composed of polyethylene terephthalate, the other components to be copolymerized are preferably 10 mol% or less from the viewpoint of heat resistance.

  The non-woven web layer made of a polylactic acid-based polymer and the non-woven web layer made of an aromatic polyester-based polymer constituting the laminated non-woven fabric are in a mass ratio of (non-woven web layer made of a polylactic acid-based polymer) / (Nonwoven web layer made of an aromatic polyester polymer) It is preferably laminated at a ratio of 40/60 to 75/25. When the proportion of the nonwoven web layer made of a polylactic acid polymer is less than 40% by mass, it is difficult to be included in the concept of “nonwoven fabric made of plant-derived resin” which is the gist of the present invention. In addition, when the proportion of the nonwoven web layer made of a polylactic acid polymer is larger than 75% by mass, the proportion of the nonwoven web layer made of an aromatic polyester polymer is lowered by that amount, so that the nonwoven fabric at high temperature The mechanical properties of are reduced. For this reason, when the nonwoven fabric of the present invention is used as a base fabric for a thermoforming carpet, for example, there is a risk of problems such as tearing during thermoforming of the carpet after tufting and backing.

  Various additives such as a matting agent, a pigment, and a crystal nucleating agent may be added to the polylactic acid polymer and the aromatic polyester polymer, respectively, as long as they do not impair the effects of the present invention. Good. In particular, it is preferable to add a crystal nucleating agent such as talc, titanium oxide, calcium carbonate, and magnesium carbonate in order to prevent fusion (blocking) between yarns in the spinning / cooling step. This crystal nucleating agent is preferably used in the range of 0.1 to 5% by mass. If it is less than 0.1% by mass, a substantial effect by addition cannot be expected. On the other hand, when it exceeds 5% by mass, the strength of the obtained yarn is lowered and the spinning property during production is inferior.

  The fiber cross section of the constituent fiber of the polylactic acid-based nonwoven fabric of the present invention includes a normal round cross section, a hollow cross section, an irregular cross section, a parallel composite cross section, a multilayer composite cross section, a core-sheath composite cross section, a split composite cross section, etc Any fiber cross-sectional shape can be used depending on the purpose.

What is necessary is just to set the fabric weight of the polylactic acid-type nonwoven fabric of this invention suitably. For example, when this nonwoven fabric is used as a base fabric for a thermoforming carpet, the basis weight is preferably in the range of 80 to 200 g / m ² , more preferably 100 to 180 g / m ² . If the basis weight is less than 80 g / m ² , tearing is likely to occur during thermoforming during carpet production. On the other hand, if the basis weight exceeds 200 g / m ² , the fiber amount of the base fabric is large, and the pile height is likely to be uneven or the tuft intervals are likely to be uneven. Moreover, it is disadvantageous in terms of cost.

  The polylactic acid-based nonwoven fabric having a laminated structure according to the present invention comprises a nonwoven web layer formed of a polylactic acid polymer and a nonwoven web layer formed of an aromatic polyester polymer. Integrated by three-dimensional confounding. With such a configuration, since the constituent fibers are entangled not only in the two-dimensional direction, that is, in the surface direction of the nonwoven fabric, but also in the thickness direction of the nonwoven fabric, there is an advantage that delamination hardly occurs. In particular, the constituent fibers formed of the polylactic acid polymer and the constituent fibers formed of the aromatic polyester polymer are intertwined in the three-dimensional direction, so that the polylactic acid nonwoven web layer In addition, there are fibers of aromatic polyester polymer, and aromatic polyester polymer has higher glass transition temperature and higher crystallinity than polylactic acid. The mechanical strength can be maintained, and the form stability is improved.

  When the nonwoven fabric of the present invention is used as a base fabric for a thermoforming carpet, the constituent fibers are entangled three-dimensionally, that is, in the thickness direction. The cloth does not cause delamination, and the form retainability can be improved.

  A needle punching process is suitable as a method for three-dimensionally entanglement of the constituent fibers. This is because the constituent fibers are strongly pushed in with a high-stiffness needle, so that the entanglement between the constituent fibers becomes good between both web layers along the thickness direction of the nonwoven fabric.

The needle density during needle punching is preferably 20 to 100 times / cm ² . When the needle density is less than 20 times / cm ² , the degree of entanglement between the long fibers is low, and the effect of applying needle punch cannot be exhibited. On the other hand, when the needle density exceeds 100 times / cm ² , the long fibers are severely damaged, and the fibers themselves become extremely low in strength, so that the mechanical strength of the nonwoven fabric tends to be inferior.

  In the polylactic acid-based nonwoven fabric of the present invention, in order to improve the stress and tensile strength at the time of elongation, it is preferable to adhere a contact point between constituent fibers by attaching a binder resin to the base fabric. It is preferable that the adhesion amount (solid content adhesion amount) of binder resin is 2-15 mass% with respect to the total mass of a nonwoven fabric. If the adhesion amount of the resin is less than 2% by mass, the effect of imparting the binder resin cannot be exhibited. On the other hand, when the adhesion amount exceeds 15% by mass, the resin existing between the long fibers becomes too much. For this reason, when the adhesion amount exceeds 15% by mass, the degree of freedom of the fibers is lost when tufting the pile yarn when the nonwoven fabric of the present invention is used as a base fabric for a thermoforming carpet. Tinging needles do not easily penetrate the base fabric, and the resulting carpet tends to be less flexible.

  As the binder resin, the above-described polylactic acid polymer used for nonwoven fabrics can be suitably used. Polysaccharides such as polyvinyl alcohol and natural starch such as starch, protein, chitosan and the like may also be used. In addition, as long as the mass of the polylactic acid polymer in the total mass of the nonwoven fabric is 40% by mass or more, conventionally used methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, methacryl A copolymer obtained by combining two or more monomers such as ethyl acid, butyl methacrylate, acrylonitrile, and styrene and copolymerizing at a desired molar ratio can also be employed. Moreover, you may use the bridge | crosslinking type binder resin which bridge | crosslinked these copolymers with crosslinking agents, such as a melamine resin and a phenol resin.

  In the case where the nonwoven fabric of the present invention is used as a base fabric for a thermoforming carpet, the maximum strength at 130 ° C. is 50 N / 5 cm width or more in both the vertical and horizontal directions in consideration of thermoformability, and The elongation at break is preferably 50% or more in both the vertical and horizontal directions. If the maximum strength is less than 50 N / 5 cm width and the elongation at break is less than 50%, it cannot follow the molding die and is easily broken during thermoforming. As the upper limit, the strength may be 150 N / 5 cm width and the elongation may be about 150%.

  Further, at the time of thermoforming, it is preferable to have an appropriate stress at the time of initial elongation, and the stress at 10% elongation at 130 ° C. is preferably 10 N / 5 cm width or more in both the vertical direction and the horizontal direction. More preferably, the width is 20 N / 5 cm or more. When the width is less than 10 N / 5 cm, it does not extend evenly, but locally extends in a deep drawing portion or the like, and a thin portion tends to occur. On the other hand, the upper limit of the stress is not particularly limited, but may be about 60 N / 5 cm width.

  Next, the manufacturing method of the polylactic acid-type nonwoven fabric of this invention is demonstrated. Both the long fiber nonwoven web layer formed of the polylactic acid-based polymer constituting the nonwoven fabric of the present invention and the long fiber nonwoven web layer formed of the aromatic polyester polymer are both so-called spunbonds. It can be manufactured efficiently by the method.

  That is, first, a polylactic acid polymer and an aromatic polyester polymer are prepared. The prepared polylactic acid polymer and aromatic polyester polymer are melt-metered by individual melt extruders, melt-spun through a predetermined spinneret, and the spun yarn spun from the above-mentioned spinneret is conventionally known. After being cooled using a cooling device such as a horizontal spray or an annular spray, it is pulled down and pulled using a suction device.

  The pulling speed at this time is preferably set to 3000 to 6000 m / min, and more preferably 4000 to 6000 m / min. When the pulling speed is less than 3000 m / min, the molecular orientation is not sufficiently promoted in the yarn, and the dimensional stability of the finally obtained nonwoven fabric is inferior. On the other hand, if the pulling speed is too high, the spinning stability is poor.

  The stretched long fibers are opened using a known opening device, and then spread and deposited on a movable collection surface such as a screen conveyor to form both nonwoven web layers. Laminate the layers. At this time, it is appropriately selected which of the nonwoven web layer made of a polylactic acid polymer and the nonwoven web layer made of an aromatic polyester polymer is used as an upper layer.

  Thereafter, the laminated nonwoven web layers are subjected to partial thermocompression bonding using a thermocompression bonding apparatus to temporarily integrate them. When the partial thermocompression treatment is performed, a method of forming a spot-like fusion zone on a nonwoven web using a heated embossing roll and a metal roll having a smooth surface is preferable. The temperature during the heat treatment may be set to a temperature at which the polylactic acid polymer melts or softens, but is appropriately selected depending on the treatment time and the like.

  The nonwoven web layer made of the laminated polylactic acid polymer and the nonwoven web layer made of the aromatic polyester polymer are entangled and integrated by needle punching. The needle density conditions at that time are as described above. At this time, it is preferable to pass the needle from the nonwoven web layer made of the aromatic polyester polymer. This is because fibers made of an aromatic polyester polymer having excellent heat resistance can be actively incorporated into the nonwoven web layer made of a polylactic acid polymer. Thus, a laminated nonwoven fabric is formed, and if necessary, a desired amount of binder resin is adhered in the manner described above to obtain the polylactic acid-based nonwoven fabric of the present invention.

  When using the nonwoven fabric of the present invention as a base fabric for a thermoforming carpet, after obtaining a living machine by tufting to the obtained polylactic acid-based nonwoven fabric using a desired pile yarn, after performing a backing treatment, A molded tufted carpet can be obtained by thermoforming with a desired mold.

[Example]
Next, based on an Example, this invention is demonstrated concretely. However, the present invention is not limited only to these examples. In addition, the measurement of the various physical-property values in the following examples and comparative examples was implemented with the following method.

(1) Melt flow rate value (hereinafter referred to as “MFR value”) [g / 10 min]: Measured at a load of 2160 gf and a temperature of 210 ° C. according to the method described in ASTM-D-1238 (E).

(2) Relative viscosity (ηrel): 0.5 g of a sample was dissolved in 100 cc of a mixed solvent having an equal mass ratio of phenol and ethane tetrachloride and measured using an Ostwald viscometer.

(3) Melting point [° C.] Using a differential scanning calorimeter (Perkin Elma, DSC-2 type), the sample weight was measured at 5 mg and the heating rate was 10 ° C./min. The temperature giving the maximum value of the curve was defined as the melting point [° C.].

(4) Weight per unit area [g / m ² ]: Ten sample pieces having a sample length of 10 cm and a sample width of 5 cm were prepared from a sample in a standard state, and after making the equilibrium moisture, the weight (g) of each sample piece was determined. Weighing was performed, and the average value of the obtained values was converted per unit area to obtain a basis weight [g / m ² ].

(5) Tensile strength [N / 5 cm width], elongation [%] in a normal temperature atmosphere: Ten strip-shaped test pieces having a width of 5 cm and a length of 30 cm were prepared. Using Tensilon UTM-4-1-100 manufactured by Win Co., Ltd., a tensile test was performed at a gripping interval of 10 cm and a tensile speed of 20 cm / min, and the measurement was performed according to JIS L 1906. And the average value of 10 points | pieces was made into tensile strength [N / 5cm width]. Further, the elongation [%] at the time of cutting obtained under the above conditions was defined as the elongation at break [%].

(6) Tensile strength [N / 5 cm width] under high temperature atmosphere, elongation (%): Measured according to JIS-L-1906 under a high temperature atmosphere of 130 ° C. That is, 10 pieces of sample pieces each having a width of 5 cm and a length of 20 cm were produced in the vertical direction and the horizontal direction of the nonwoven fabric. After using a constant speed extension type tensile testing machine (Tensilon UTM-4-1-100 manufactured by Orientec Co., Ltd.) in a high temperature atmosphere of 130 ° C., holding a sample piece at a spacing of 10 cm and leaving it for 5 minutes, Stretching at a tensile speed of 20 cm / min, the average value of 10 points for the obtained load value at the time of cutting [N / 5 cm width] is the tensile strength [N / 5 cm width] in a high temperature atmosphere, and elongation at break The average value of 10 points was defined as the elongation at break [%] in a high-temperature atmosphere.

Example 1
L-lactic acid / D-lactic acid = 98.6 / 1.4 mol% L-lactic acid / D-lactic acid copolymer having a melting point of 168 ° C. and an MFR of 70 g / 10 min contains 0.5% by mass of talc. Using the prepared one, melt spinning was performed from a round spinneret at a spinning temperature of 210 ° C. and a single hole discharge rate of 1.67 g / min. Next, the spun yarn shape is cooled with a cooling air flow, and subsequently taken up at 5000 m / min with an air soccer ball, which is opened and deposited on the collecting surface of a moving conveyor to obtain a single yarn fineness. A non-woven web layer having a basis weight of 70 g / m ^{2 made} of 3 dtex polylactic acid long fibers was formed.

On the other hand, polyethylene terephthalate having a relative viscosity of 1.38 and a melting point of 256 ° C. was melt-spun at a spinning temperature of 285 ° C. from a round spinneret at a single hole discharge rate of 1.67 g / min. Next, the spun yarn shape is cooled with a cooling air flow, and subsequently taken up at 5000 m / min with an air soccer ball, which is opened and deposited on a collecting surface of a moving conveyor to obtain a single yarn fineness of 3 A long-fiber nonwoven web layer made of polyethylene terephthalate having a weight of .3 dtex and a basis weight of 60 g / m ² was obtained.

A non-woven web layer made of a polylactic acid polymer is laminated on a non-woven web layer made of polyethylene terephthalate, and the obtained laminated web is passed through a partial thermocompression bonding device made of an embossing roll. A laminated long fiber web was obtained by partial thermocompression bonding under the conditions of a rate of 14.9%, a compression point density of 21.9 pieces / cm ² , and a linear pressure of 30 kg / cm.

Next, 0.5% by mass of a silicone-based oil agent is adhered to the laminated nonwoven web, and needles are passed through the needle from the nonwoven web layer made of polyethylene terephthalate by needle punching. The laminated nonwoven web was integrated by intertwining the constituent fibers of the woven web layer with the constituent fibers of the nonwoven web layer made of a polylactic acid-based polymer. The needle punching conditions were a needle density of 45 times / cm ² and a needle depth of 12 mm. Thereafter, 14% by mass of an acrylic binder resin was adhered to obtain a polylactic acid nonwoven fabric having a basis weight of 150 g / m ² .

  The physical properties of the nonwoven fabric thus obtained are shown in Table 1.

(Examples 2 to 5)
The basis weight of the nonwoven web made of a polylactic acid polymer and the basis weight of the nonwoven web made of polyethylene terephthalate were changed as shown in Table 1, respectively. As a result, the lamination ratio between the two was changed as shown in Table 1. The needle depth during the needle punching process was changed as shown in Table 1. And other than that was carried out similarly to Example 1, and obtained the polylactic acid-type nonwoven fabric.

  The physical properties of the nonwoven fabric thus obtained are shown in Table 1.

(Comparative Example 1)
A nonwoven fabric was produced only from a nonwoven web made of a polylactic acid polymer. That is, an L-lactic acid / D-lactic acid copolymer having a melting point of 168 ° C. and an MFR of 70 g / 10 min as in Example 1 and an L-lactic acid / D-lactic acid copolymer of 98.6 / 1.4 mol%. Using a round spinneret, melt spinning was performed at a spinning temperature of 210 ° C. and a single hole discharge rate of 1.67 g / min. Next, the spun yarn shape was cooled with a cooling air flow, and subsequently taken up at 5000 m / min with an air soccer ball, which was opened and deposited on the collecting surface of a moving conveyor to form a web. . Next, the web was passed through a partial thermocompression bonding apparatus composed of an embossing roll, and the part was temporarily formed under the conditions of a roll temperature of 100 ° C., a crimping area ratio of 14.9%, a crimping point density of 21.9 pieces / cm ² , and a linear pressure of 60 kg / cm. Thus, a non-woven long-fiber web having a basis weight of 135 g / m ² made of only a polylactic acid polymer long fiber having a single yarn fineness of 3.3 dtex was obtained.

Next, 0.5% by mass of a silicone-based oil agent was adhered to the nonwoven web consisting only of this polylactic acid polymer, and integration was performed by needle punching. The needle punching conditions were a needle density of 45 times / cm ² and a needle depth of 12 mm. Thereafter, 10% by mass of an acrylic binder resin was attached to obtain a polylactic acid nonwoven fabric having a basis weight of 150 g / m ² .

  The physical properties of the nonwoven fabric thus obtained are shown in Table 1.

  1 to 4 show the relationship between the elongation and the load when a load is applied to the sample piece in the high-temperature atmosphere described above and the elongation is gradually increased until breakage occurs. Among these, FIG. 1 shows the result about the sample of the vertical direction (MD) in Examples 1, 3, 4 and Comparative Example 1, and FIG. 2 shows the horizontal direction in Examples 1, 3, 4 and Comparative Example 1. The result about the sample of (TD) is shown. 3 shows the results for the samples in the vertical direction (MD) in Examples 1 and 5 and Comparative Example 1, and FIG. 4 shows the samples in the horizontal direction (TD) in Examples 1 and 5 and Comparative Example 1. The results are shown.

  Each of the polylactic acid-based nonwoven fabrics of Examples 1 to 5 has a maximum tensile strength of 50 N / 5 cm or more in the vertical direction and the horizontal direction in a high temperature atmosphere, and also in the vertical direction and the horizontal direction in a high temperature atmosphere. The elongation at break in the direction was 50% or more. That is, it showed good heat resistance. For this reason, it is possible to obtain non-woven fabrics with good thermoformability in high-temperature atmospheres, and it is suitable for applications that require thermoformability, such as automotive carpet base fabrics, without greatly changing the conventional material design. It was something you could expect to do.

  On the other hand, since the nonwoven fabric of Comparative Example 1 was composed of a nonwoven web composed only of polylactic acid-based fibers, both the tensile strength and the elongation under a high temperature atmosphere were those of Examples 1 to 5. The heat resistance and good thermoformability could not be expected.

It is a graph which shows an example of the relationship between elongation and a load when a load is made to act on a sample piece in a high temperature atmosphere. It is a graph which shows the other example of the relationship between elongation and a load when a load is made to act on a sample piece in a high temperature atmosphere. It is a graph which shows the further another example of the relationship between elongation and a load when a load is made to act on a sample piece in high temperature atmosphere. It is a graph which shows the further another example of the relationship between elongation and a load when a load is made to act on a sample piece in high temperature atmosphere.

Claims (4)

  A long-fiber nonwoven web layer formed of a polylactic acid-based polymer and a long-fiber nonwoven web layer formed of an aromatic polyester-based polymer are laminated and formed by three-dimensional entanglement between constituent fibers. A polylactic acid-based non-woven fabric which is integrated and has a melting point of 150 ° C. or higher.   The polylactic acid-based nonwoven fabric according to claim 1, wherein the aromatic polyester-based polymer is one of polyethylene terephthalate and a copolymer mainly composed of the polyethylene terephthalate.   It is formed of the polylactic acid-based nonwoven fabric according to claim 1 or 2, the maximum strength at 130 ° C is 50 N / 5 cm width or more in both the vertical direction and the horizontal direction, and the elongation at break at 130 ° C is the vertical direction. A polylactic acid nonwoven fabric for thermoforming, characterized in that the horizontal direction is 50% or more.   A method for producing the polylactic acid-based nonwoven fabric according to claim 1 or 2, or the polylactic acid-based nonwoven fabric for thermoforming according to claim 3, wherein the non-long fiber formed with a polylactic acid-based polymer is used. By laminating a woven web layer and a long fiber nonwoven web layer formed of an aromatic polyester polymer, through a needle from the long fiber nonwoven web layer formed of an aromatic polyester polymer, A method for producing a nonwoven fabric, wherein the constituent fibers of both nonwoven web layers are entangled and integrated by needle punching.

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