JP2009228165A - Core-sheath type binder fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a core-sheath type binder fiber, with a biomass-derived polymer as the core, suitable for obtaining a fibrous structural form with softer touch feeling, and high in abrasion resistance unlike a binde fiber composed of a biomass-derived polymer alone. <P>SOLUTION: The binder fiber comprises a core-sheath type conjugate fiber, wherein the core of the conjugate fiber is composed of polylactic acid, while the sheath thereof is composed of a copolyester lower in melting point than the above polylactic acid. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a core-sheath type binder fiber having a soft texture.

  Conventionally, among synthetic fibers composed of polyester, polyolefin, polyamide, etc., a binder fiber that functions as a thermal adhesive component by arranging a low melting point component in a sheath part and a high melting point component in a core part. It is used in various applications as a material that can easily create a fiber structure such as a nonwoven fabric by heat treatment.

  However, when these synthetic fibers are left in the natural world after use, various problems occur because they are not easily decomposed. For example, living materials, agricultural materials, and civil engineering materials made of these synthetic fibers are difficult to be decomposed. Therefore, after use, they must be buried in the soil or incinerated. There was a limit, and a large amount of heat was required for incineration.

  Moreover, most of the conventional synthetic fibers are made from valuable fossil resources such as petroleum, but in recent years, the fossil resources are not only concerned about the shortage of resources, but also the amount of carbon dioxide generated. It has a great impact on society. Under such a social background, carbon dioxide fixation is expected to be effective in preventing global warming, and carbon dioxide fixation substances are particularly focused on the Kyoto Protocol that imposes a target value for carbon dioxide reduction. The degree is high, and the use of biomass-derived substances is desired. Carbon dioxide produced when the biomass-derived synthetic fiber or synthetic resin is burned is originally in the air, and carbon dioxide in the atmosphere does not increase. This is called carbon neutral and tends to be regarded as important.

  Due to the above problems, so-called biodegradable resins that are degradable in nature have been actively developed. Among them, polylactic acid having excellent heat resistance and yarn-making property has attracted attention, and binder fibers using polylactic acid as a raw material have been studied.

For example, Patent Document 1 proposes a binder fiber in which polylactic acid having a low melting point is disposed in the sheath portion and polylactic acid having a high melting point is disposed in the core portion. However, when this binder fiber is made into a nonwoven fabric by heat treatment, the heat-bonded portion of the remelted sheath portion is very strong due to the nature of polylactic acid, and the resulting nonwoven fabric lacks softness.
Japanese Patent No. 3355026

  The present invention is intended to provide a core-sheath binder fiber in which a biomass-derived polymer is arranged in a core part, which is suitable for solving the above-described problems and obtaining a fiber structure having a softer texture.

As a result of intensive studies to solve the above problems, the present inventors have reached the present invention.
That is, the gist of the present invention is as follows.
(A) A binder fiber composed of a core-sheath type composite fiber, wherein the core part of the composite fiber is made of polylactic acid and the sheath part is made of a copolyester having a melting point lower than that of the polylactic acid. Core sheath type binder fiber.

  The core-sheath-type binder fiber of the present invention has a biomass-derived polymer arranged in the core, so that unlike a conventional binder fiber made only of a petroleum-derived polymer, it is a novel material that is contrary to carbon neutral when discarded. Since the generation of carbon dioxide is reduced, the environmental load is small. Moreover, since the low melting point copolyester is arranged in the sheath, unlike the binder fiber made only of the biomass-derived polymer, it has an effect of excellent wear resistance.

Hereinafter, the present invention will be described in detail.
The core-sheath binder fiber of the present invention (hereinafter sometimes referred to as the binder fiber of the present invention) has a core-sheath type composite form, and the core is composed of polylactic acid.

  Examples of the polylactic acid constituting the core include poly D-lactic acid, poly L-lactic acid, poly DL-lactic acid that is a copolymer of poly D-lactic acid and poly L-lactic acid, poly D-lactic acid, and poly L-lactic acid. A mixture of lactic acid (stereo complex), a copolymer of poly D-lactic acid and hydroxycarboxylic acid, a copolymer of poly L-lactic acid and hydroxycarboxylic acid, poly D-lactic acid or poly L-lactic acid and aliphatic polyester It is preferable to make it a copolymer or a blend thereof.

  The polylactic acid is one in which L-lactic acid and D-lactic acid are used alone or in combination as described above. Among them, the melting point is 120 ° C. or more, and the heat of fusion is 10 J / g or more. It is preferable that the melting point is 150 ° C. or higher. The melting point of L-lactic acid and D-lactic acid, which are homopolymers of polylactic acid, is about 180 ° C., but in the case of a copolymer of D-lactic acid and L-lactic acid, the proportion of any component is about 10 mol%. Then, the melting point is about 130 ° C. Furthermore, when the proportion of any of the components is 18 mol% or more, the melting point is less than 120 ° C., and almost completely amorphous properties are obtained. Therefore, when it becomes such an amorphous polymer, it becomes difficult to heat-stretch especially in a manufacturing process, and the problem that it becomes difficult to obtain a high intensity | strength fiber arises. Also, since the melting point difference with the sheath component is small, when the processing temperature is lowered to a temperature at which the core is not easily affected by heat during thermal bonding, the thermal bonding component does not melt sufficiently and the thermal adhesiveness decreases. May end up.

  Among polylactic acids, a mixture (stereo complex) of poly D-lactic acid and poly L-lactic acid as described above is particularly preferable because it has a high melting point of 200 to 230 ° C. and is hardly affected by frictional heat. In the case of a copolymer of polylactic acid and hydroxycarboxylic acid, specific examples of hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid, etc. Can be mentioned. Of these, the use of hydroxycaproic acid or glycolic acid is preferable from the viewpoint of cost. In the case of a copolymer of polylactic acid and aliphatic polyester, as the aliphatic dicarboxylic acid and aliphatic glycol constituting this, sebacic acid, adipic acid, dodecanedioic acid, trimethylene glycol, 1,4-butanediol, Examples include 1,6-hexanediol. Thus, when making polylactic acid copolymerize another component, it is preferable that polylactic acid shall be 80 mol% or more. If it is less than 80 mol%, the crystallinity of the copolymerized polylactic acid tends to be low, and the melting point is less than 120 ° C. and the heat of fusion is less than 10 J / g.

The molecular weight of the polylactic acid in the present invention is 1 to 100 (g / 10 min) as measured by a temperature of 210 ° C. and a load of 2160 g according to ASTM D-1238 method used as an index of molecular weight. It is preferable that it is 5 to 50 (g / 10 min). That is, by setting the melt flow rate within this range, the strength, wet heat decomposability, and wear resistance are improved.
In order to increase the durability of the polylactic acid in the binder fiber of the present invention, a terminal blocking agent such as an aliphatic alcohol, a carbodiimide compound, an oxazoline compound, an oxazine compound, or an epoxy compound may be added to the polylactic acid. Furthermore, as long as it does not impair the purpose of the present invention, a heat stabilizer, a crystal nucleating agent, a matting agent, a pigment, a light-proofing agent, a weathering agent, a lubricant, an antioxidant, an antibacterial agent are included in polylactic acid as necessary. Agents, fragrances, plasticizers, dyes, surfactants, flame retardants, surface modifiers, various inorganic and organic electrolytes, and other similar additives may be added.

  The copolymer polyester constituting the sheath in the binder fiber of the present invention may have a lower melting point than the polylactic acid constituting the core, but the difference in melting point from the copolymer polyester constituting the core is 30 ° C. or more. Is more preferable, and more preferably 50 ° C. or higher. When the difference in melting point is less than 30 ° C., the melting point is close to that of the core component, and it is necessary to lower the heat treatment temperature in order to make the core part less susceptible to heat during heat treatment. Is not preferable because it does not melt sufficiently and adhesiveness decreases.

  Moreover, as melting | fusing point of the copolyester which comprises the sheath part in the binder fiber of this invention, it is preferable that it is 90 degreeC or more. When the melting point is less than 90 ° C., the binder fibers tend to adhere to each other at the time of spinning or stretching, and the operability tends to be inferior.

  The copolyester constituting the sheath in the binder fiber of the present invention includes aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 5-sulfoisophthalic acid, adipic acid, and succinic acid in view of viscosity, thermal characteristics, and compatibility. Aliphatic dicarboxylic acids such as acid, suberic acid, sebacic acid, dodecanedioic acid, and aliphatic such as 1,6-hexanediol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol Copolymers formed by copolymerizing diols, glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxypentanoic acid, hydroxyheptanoic acid, hydroxyoctanoic acid and other aliphatic lactones, and ε-caprolactone. Be a polymerized polyester Preferred.

  As a particularly preferred copolyester, a copolyester containing a terephthalic acid component and a 1,6-hexanediol component, wherein terephthalic acid is 60 mol% or more based on the total acid component of the polyester, On the other hand, a copolyester having a constitution in which 1,6-hexanediol is 60 to 95 mol% and ethylene glycol is 5 to 40 mol% can be mentioned. Incidentally, since the melting point exceeds 150 ° C. when the copolymerization ratio of 1,6-hexanediol as the diol component is less than 60 mol%, it does not have adhesiveness in a low temperature range, which is a feature of the present invention. Not preferable.

  Since the binder fiber of the present invention is provided with the sheath portion having the above-described component structure, it can exhibit excellent wear resistance together with a soft texture.

  In addition, various additives, thickeners, and known additives that are effective as crystal nucleating agents may be added to the copolyester of the sheath part and the polylactic acid of the core part of the binder fiber of the present invention as necessary. it can. Specifically, carbon black, calcium carbonate, silicon oxide and silicate, zinc white, high-site clay, kaolin, basic magnesium carbonate, mica, talc, quartz powder, diatomaceous earth, dolomite powder, titanium oxide, zinc oxide , Antimony oxide, barium sulfate, calcium sulfate, alumina, calcium silicate, boron nitride, behenamide, aliphatic amide compounds, aliphatic urea compounds, benzylidene sorbitol compounds, crosslinked polymer polystyrene, rosin metal salts And glass fiber and whiskers. The substance may be added as it is, or may be added after necessary treatment as a nanocomposite. In order to achieve a good price and good physical property balance, an inorganic filler is preferably blended. In addition, a crystal nucleating agent is preferably blended, and an inorganic particle nucleating agent mainly composed of silicon oxide such as talc or silica is particularly effective in preventing the fusion of single yarns during melt spinning.

  If necessary, colorants such as pigments and dyes, odor absorbers such as activated carbon and zeolite, fragrances such as vanillin and dextrin, stabilizers such as antioxidants and UV absorbers, lubricants, mold release agents, and repellents. Water solution, antibacterial agent and other secondary additives can be blended.

  Furthermore, a plasticizer can be used in combination with the composition constituting the core-sheath portion of the binder fiber of the present invention as long as the effects of the present invention are not impaired. By using a plasticizer, it is possible to reduce the melt viscosity during heat processing, especially during extrusion processing, and to suppress a decrease in molecular weight due to shearing heat generation, etc.In some cases, an improvement in crystallization speed can also be expected. Furthermore, when a film or sheet is obtained as a molded product, extensibility and the like can be imparted.

  Although there is no limitation in particular as a plasticizer which can be used, the following can be illustrated. As the plasticizer for the aliphatic polyester-based biodegradable polyester, ether-based plasticizers, ester-based plasticizers, phthalic acid-based plasticizers, phosphorus-based plasticizers, and the like are preferable, and ether-based plasticizers are excellent in compatibility with polyesters. Agents and ester plasticizers are more preferred. Examples of ether plasticizers include polyoxyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Examples of ester plasticizers include esters of aliphatic dicarboxylic acids and aliphatic alcohols. Examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, sebacic acid, and adipic acid. Examples of aliphatic alcohols include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, n-hexanol, n-octanol, 2-ethylhexanol, n-dodecanol, stearyl alcohol, ethylene glycol, 1,2- Propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, dihydric alcohols such as diethylene glycol, neopentyl glycol, polyethylene glycol, and glycerin Trimethylolpropane, it may be mentioned polyhydric alcohols pentaerythritol and the like. In addition, two or more kinds of blends selected from copolymers, di-copolymers, tri-copolymers, tetra-copolymers, etc., or homopolymers, copolymers, etc. composed of combinations of two or more of the above polyethers and polyesters. Can be mentioned. Furthermore, the esterified hydroxycarboxylic acid etc. are mentioned. At least one kind of the plasticizer can be used.

  The binder fiber of the present invention may be a multifilament composed of a plurality of single yarns or a monofilament composed of a single yarn. In the case of a multifilament, the single yarn fineness is preferably 1 to 200 dtex, and the total fineness is preferably 36 to 5000 dtex, and particularly preferably 36 to 1500 dtex. In the case of a monofilament, the fineness is preferably set to 150 to 5000 dtex.

Moreover, as a binder fiber of this invention, you may use with the form of either a long fiber or a short fiber. Furthermore, the shape of the binder fiber of the present invention is not limited to a circular cross-section, as long as the polylactic acid of the core is covered with the copolymer polyester of the sheath, a square, a polygon, It may be a multi-leaf type, a gourd type, an alphabet type, or other various non-circular shapes (atypical types).
The above-described composite fiber is preferably a concentric core-sheath type composite fiber in which the core portion and the sheath portion are arranged substantially concentrically. By setting it as such a structure, the effect which distributes a general purpose polymer uniformly to a sheath part can be show | played. If it exists on the eccentricity, a thin portion is formed in the copolyester layer of the sheath portion, and there is a possibility that the wear resistance may be poor in the portion where the copolyester layer is thin.

  Next, the manufacturing method of the binder fiber (multifilament, long fiber) of this invention is demonstrated. First, in spinning, melt spinning is performed using an ordinary composite spinning device so that polylactic acid is disposed in the core and the above-mentioned copolymer polyester is disposed in the sheath, and then the yarn is cooled and an oil agent is applied. Then, after being wound up as an undrawn yarn, or without being wound up once, it is continuously drawn.

  Examples of the use of the binder fiber of the present invention include cold chilling. When the binder fiber of the present invention is used for a cold chill, a cold chill having sufficient slip resistance can be obtained only by heat treatment without performing resin processing such as poval treatment.

Next, although an Example is given and this invention is demonstrated in detail, it is not limited to this. In addition, the measuring method and evaluation method of each physical property value in an Example are as follows.
(1) Melting point of polylactic acid (° C)
A differential scanning calorimeter DSC-2 manufactured by Perkin Elmer was used, and the measurement was carried out by a usual method under the condition of a heating rate of 20 ° C./min.
(2) Content ratio (molar ratio) of L-lactic acid and D-lactic acid in polylactic acid
It measured by the high performance liquid chromatography (HPLC) method by using the equal mass mixed solution of the ultrapure water and the methanol solution of 1N sodium hydroxide as a solvent. The column used was sumichiral OA6100, and was detected by a UV absorption measuring device.
(3) Fiber fineness (dtex)
It measured according to JIS L-1013 positive fineness.
(4) Bending wear resistance (times)
A load of 150 g was applied to the obtained multifilament, and it was brought into contact with a round cross-section metal rod with a diameter of 20 mm wound with a sand paper of SIANOR # 1600 at an angle of 90 degrees, a traverse speed of 6.7 mm / min, and a stroke speed of 35 Reciprocating friction was performed under a speed condition of times / min, and the number of times until the multifilament was broken was measured. (Passed over 300 times.)

Example 1
As the polylactic acid of the core component, one having a melting point of 170 ° C. and the content ratio of L-lactic acid and D-lactic acid of 98.5 / 1.5 is used, and as the aromatic polyester of the sheath component, the acid component is Using a copolymerized polyester (melting point 110 ° C.) having 60 mol% terephthalic acid and 40 mol% isophthalic acid and ethylene glycol as the glycol component, each chip was dried under reduced pressure and then supplied to a concentric core-sheath type compound melt spinning apparatus. Then, melt spinning was performed. At this time, it is arranged so that the copolymerized PET is the sheath and the polylactic acid is the core, the composite ratio (mass ratio) is 50/50, and the spinneret (surface diameter 230 mmφ, hole diameter 0.35 mmφ, number of holes 140 holes) ), The melt was spun at a spinning temperature of 240 ° C., and then the yarn was cooled, applied with an oil, and once scraped off. The obtained undrawn yarn was hot drawn between hot rollers heated to 90 ° C. so that the draw ratio was 5.8 times, and wound at 450 m / min to obtain a multifilament having a total fineness of 1120 dtex and 140 filaments. Obtained.

(Example 2)
As the aromatic polyester of the sheath component, the acid component consists of terephthalic acid, the glycol component consists of 15 mol% of ethylene glycol and 85 mol% of 1,6-hexanediol, and contains 0.5% by mass of talc as a crystal nucleating agent. A multifilament of Example 2 was obtained in the same manner as in Example 1 except that a copolymerized polyester (melting point: 128 ° C.) was used.

(Example 3)
As the aromatic polyester of the sheath component, the acid component is composed of terephthalic acid, the glycol component is composed of 20 mol% of 1,4-butanediol and 80 mol% of 1,6-hexanediol, and 0.5% by mass as a crystal nucleating agent A multifilament of Example 3 was obtained in the same manner as in Example 1 except that a copolyester containing talc (melting point: 130 ° C.) was used.

Example 4
The core component polylactic acid having a melting point of 150 ° C. and the content ratio of L-lactic acid and D-lactic acid of 94.2 / 5.8 is used. A multifilament of Example 4 was obtained in the same manner as in Example 1 except that a copolymerized polyester (melting point: 110 ° C.) in which 60 mol% of terephthalic acid and 40 mol% of isophthalic acid were used and the glycol component was ethylene glycol was used.

(Comparative Example 1)
As the polylactic acid of the core component, one having a melting point of 170 ° C. and a content ratio of L-lactic acid and D-lactic acid of 98.5 / 1.5 is used. The sheath component has a melting point of 150 ° C. and L-lactic acid. Using polylactic acid having an L / D ratio of 94.2 / 5.8, which is the content ratio of D-lactic acid, each chip is dried under reduced pressure, and then supplied to a concentric core-sheath type compound melt spinning apparatus to perform melt spinning. It was. At this time, the low melting point polylactic acid is arranged as a sheath part and the high melting point polylactic acid becomes the core part, the composite ratio (mass ratio) is 50/50, and the spinneret (surface diameter 230 mmφ, pore diameter 0.35 mmφ). After the melt spinning at a spinning temperature of 240 ° C., the yarn is cooled, applied with an oil agent, and scraped off once. Comparative Example 1 in which the obtained undrawn yarn was hot drawn between hot rollers heated to 90 ° C. so that the draw ratio was 6.3 times, wound at 450 m / min, and having a total fineness of 1100 dtex and 140 filaments Of multifilaments were obtained.

(Comparative Example 2)
Comparative Example 2 was carried out in the same manner as Comparative Example 1, except that polylactic acid having a melting point of 130 ° C. and an L / D content ratio of 90.0 / 10.0 was used. Of multifilaments were obtained.
(Comparative Example 3)
Comparative Example 3 was carried out in the same manner as Comparative Example 1, except that polylactic acid having a melting point of 120 ° C. and an L / D content ratio of L-lactic acid to D-lactic acid of 82.0 / 18.0 was used as the sheath component. Of multifilaments were obtained.

(Comparative Example 4)
As the polylactic acid of the core component, one having a melting point of 150 ° C., a content ratio of L-lactic acid and D-lactic acid of 94.2 / 5.8, a sheath component having a melting point of 130 ° C., and L-lactic acid A multifilament of Comparative Example 4 was obtained in the same manner as Comparative Example 1 except that polylactic acid having a D / lactic acid content ratio of L / D of 90.0 / 10.0 was used.
(Comparative Example 5)
Comparative Example 5 was performed in the same manner as Comparative Example 4 except that polylactic acid having a melting point of 120 ° C. and an L / D ratio of 82.0 / 18.0 as the content ratio of L-lactic acid and D-lactic acid was used as the sheath component. Of multifilaments were obtained.

  The physical property values of the multifilaments obtained in Examples 1 to 4 are shown in Table 1, and the physical property values of the multifilaments obtained in Comparative Examples 1 to 5 are shown in Table 2.

As is clear from Table 1, the polylactic acid composite binder fibers of Examples 1 to 4 were excellent in bending wear resistance by providing a copolymer polyester in the sheath portion. On the other hand, as is clear from Table 2, since the polylactic acid binder fibers of Comparative Examples 1 to 5 are arranged with polylactic acid, which is a polymer derived from biomass, in the core part and the sheath part, Examples 1-4 Compared with the polylactic acid composite binder fiber, the abrasion resistance was inferior.

Claims (1)

A binder fiber comprising a core-sheath type composite fiber, wherein the core part of the composite fiber is made of polylactic acid, and the sheath part is made of a copolyester having a melting point lower than that of the polylactic acid. Binder fiber.