KR20130112464A - Sheath-core all-in-one poly lactic acid fiber and a fabrication process thereof - Google Patents

Abstract

PURPOSE: An integrated outer cover-core poly lactic acid fiber, and a manufacturing method thereof are provided to have excellent durability and mechanical strength. CONSTITUTION: An integrated outer cover-core poly lactic acid fiber comprises a structure taking poly lactic acid as core, and thermoplastic polymer is surrounding the core as an outer cover. The fiber comprises: 20-40 wt% of poly lactic acid; and 60-80 wt% of thermoplastic polymer. The poly lactic acid is fermentation-synthesized from biomass. The poly lactic acid is PLLA, PDLA, or their mixture. The thermoplastic polymer is more than one selected among polypropylene, polyethylene, polyester, polyamide, polycarbonate, styrene group, and polyolefin. [Reference numerals] (AA) Polypropylene melt resin; (BB) Poly lactic acid melt resin; (CC) Sheath-core radiation

Description

Shell-core all-in-one polylactic acid fiber and a fabrication process

The present invention relates to an outer shell-core integrated polylactic acid fiber for automobile interior parts, which is made of a thermoplastic polymer having excellent high temperature mechanical properties on its outer shell and a polylactic acid which is a biodegradable polymer on its core, and a manufacturing method thereof.

Recently, the development of polymer materials that decompose in the natural environment is urgently demanded for environmental problems on the global scale, and research and development of various polymers such as aliphatic polyesters are also actively attempted to be put to practical use. Attention is focused on polymers that are degraded by living things, that is, biodegradable polymers.

However, since most polymers use petroleum resources as raw materials, there is a possibility that the petroleum resources will be depleted in the future, and global warming will become more severe as carbon dioxide, which has been accumulated in the ground since the geological era, is released into the atmosphere by consuming large amounts of petroleum resources. This phenomenon is concerned.

Therefore, if polymers can be synthesized using plant resources that inhale and grow carbon dioxide from the atmosphere, it can be expected not only to suppress global warming by the carbon dioxide cycle but also to solve the problem of exhaustion of petroleum resources. For this reason, a great deal of attention is focused on polymers using plant resources, that is, biodegradable polymers using biomass, and are expected to replace conventional polymers.

However, biodegradable polymers using biomass are generally biodegradable polymers that can solve this problem because of low mechanical properties, heat resistance, and high cost, and poly lactic acid, PLA )to be. Polylactic acid is a polymer based on lactic acid obtained by fermenting starch extracted from plants. Among biodegradable polymers using biomass, optical properties, heat resistance, and cost balance are the best, and thus, fiber development using the same is rapidly performed. have.

But even this most promising polylactic acid has some drawbacks compared to conventional polymers. The major drawback is the poor high temperature dynamics. The bad high temperature dynamics here means that it rapidly softens when the glass transition temperature (Tg) of the polylactic acid polymer exceeds 60 ° C. Nylon 6, a conventional polymer, has a softening phenomenon and exhibits sufficient mechanical properties even at 90 ° C, whereas polylactic acid fiber softens rapidly from around 70 ° C and closes to flow at 90 ° C when the tensile test is performed by changing the temperature. While showing the shape, the dimensional stability is greatly reduced.

Korean Patent Laid-Open Publication No. 2011-0036876 with respect to a fiber using such a polylactic acid includes a step of coextrusion of a core component and a sheath component, and the core component includes a polyolefin (polypropylene) and an epoxy functionalized polyolefin, and A method for preparing a polymer composition comprising polylactic acid, which is characterized in that the component comprises polylactic acid, has been proposed. However, since the polylactic acid is located in the outer layer, durability problems may occur at high temperatures.

Japanese Laid-Open Patent Publication No. 2008-0057095 proposes a lining material including a fiber coated with a polylactic acid resin by a thermoplastic resin such as another polypropylene, and Japanese Laid-Open Patent Publication No. 2008-0280665 a core is a polylactic acid. A sheath is a polypropylene-based polymer, and has been proposed for a sheath composite fiber containing a colored pigment having a mass reduction rate of 20 mass% or less before and after hydrolysis treatment.

In addition, Japanese Patent Laid-Open No. 2000-248426 discloses obtaining a high strength yarn by multi-stretching a polylactic acid non-stretched yarn obtained by low speed spinning in an existing study.

However, the above methods produce fibers made of polylactic acid and thermoplastic resins. These methods are obtained by multistage stretching, not two-stage stretching, and have a physical strength of 7 cN / dtex at room temperature but high mechanical properties. It appears that the practical level is not reached.

As mentioned above, the fiber using polylactic acid actually has various problems because of poor mechanical properties at high temperatures, that is, strength and creep properties. For example, when the fabric is used as a warp yarn, the yarn is fed for the purpose of improving the weaving property to increase the focusing property of the yarn. However, a problem arises in that the yarn stretches due to the tension applied due to hot wind drying. Moreover, when polylactic acid fiber is used in high temperature atmosphere, a problem arises in durability of a product. In summer, for example, temperatures in cars reach 72 ° C on the front seat surface and 80 ° C on the rear seat upper surface. When the polylactic acid fiber is applied to the car seat fabric, the durability of the sheet occurs because the sheet surface temperature exceeds the glass transition temperature (Tg) of the polylactic acid.

Therefore, polylactic acid is a biodegradable polymer that has the best balance of optical properties, heat resistance and cost, but it has a disadvantage of poor mechanical properties at high temperatures. There is a need for technology development of fibers using polylactic acid having improved.

In order to solve the problem of polylactic acid fiber whose mechanical properties are sharply deteriorated at high temperature as in the prior art, through the production and stretching of the fiber through the shell-core composite spinning of polylactic acid material and thermoplastic polymer material, through heat treatment at high temperature The invention has been completed by knowing a technology of improving heat resistance and mechanical strength.

Accordingly, an object of the present invention is to provide a sheath-core integral polylactic acid fiber composed of a polylactic acid as a core and a structure in which a thermoplastic polymer surrounds the core in the form of a sheath.

It is another object of the present invention to provide a sheath-core integral polylactic acid fiber having excellent heat resistance and mechanical strength.

The present invention is a structure in which a polylactic acid is used as a core and a thermoplastic polymer surrounds the core in the form of an outer shell, wherein the polylactic acid is 20 to 40% by weight and the thermoplastic polymer is 60 to 80% by weight. It provides a core integral polylactic acid fiber.

In another aspect, the present invention provides a method for producing a shell-core integral polylactic acid fiber,

It is composed of two parts of thermoplastic polymer resin and polylactic acid in the outer part and melt-spun through spinneret, 20 ~ 40% by weight of polylactic acid and 60 ~ 80% by weight of thermoplastic polymer. Preparing an undrawn yarn of;

Drawing the unstretched yarn melt-spun in the above step by using a first take-up roller and a second take-up roller; And

Heat treating the two-stretched fibers to produce shell-core integral polylactic acid fibers;

It provides a method for producing a shell-core integrated polylactic acid fiber comprising a.

According to the present invention, by forming a structure in which the core is polylactic acid and the thermoplastic polymer is enclosed in the outer shell form of the core, it is possible to improve the high-temperature mechanical properties to produce a sheath-core integrated polylactic acid fiber having excellent durability and mechanical strength.

In addition, it can be applied to various applications such as yarn, shirts or blouses, curtains, mats, furniture, belts, nets, ropes, felts, non-woven fabrics, artificial grasses, and the like as automotive interior parts and industrial materials.

1 shows a schematic structural diagram of a sheath-core spinner for producing polylactic acid fibers.
Figure 2 illustrates a sheath-core yarn cross-sectional structure of polylactic acid fiber according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail as an embodiment.

The present invention is a structure in which a polylactic acid is used as a core and a thermoplastic polymer surrounds the core in the form of an outer shell, wherein the polylactic acid is 20 to 40% by weight and the thermoplastic polymer is 60 to 80% by weight. A core integrated polylactic acid fiber is featured.

The polylactic acid is a polymerized lactic acid synthesized by fermentation from biomass. It is preferable to use an L- or D-type polylactic acid having a high melting point of 90% or more. Accordingly, the polylactic acid may be polylactic acid (PLLA), polyDlactic acid (PDLA), or a mixture thereof. Here, the polylactic acid (PLLA) refers to a polylactic acid having an L-type optical purity of 90% or more. Meaning, poly Dlactic acid (PDLA) means a polylactic acid composed of D-body optical purity of 90% or more. Moreover, components other than lactic acid can be copolymerized in the range which does not impair the property of a polylactic acid, and additives, such as a polymer other than polylactic acid, a particle | grain, a lubricant, a flame retardant, an antistatic agent, can be added.

In addition, the thermoplastic polymer is a thermoplastic resin having excellent mechanical properties at high temperature, it is preferable to use any one or more selected from polypropylene, polyethylene, polyester, polyamide, polycarbonate, styrene-based, polyolefin, and most preferably poly It is recommended to use propylene.

At this time, it is composed of two components of polylactic acid and thermoplastic polymer, and they are preferably 30-40% by weight of polylactic acid in the core part and 60 to 70% by weight of thermoplastic polymer in the outer skin part. If it is lower than 30% by weight, the content of the biomass-derived material decreases as the content of the biomass-derived material decreases. If it is higher than 40% by weight, the polylactic acid content is increased, but the physical properties of the final product are weakened.

The polylactic acid fiber prepared by blending, stretching, and heat treatment of such a material has a molecular weight of preferably 50,000 to 500,000 g / mol. In addition, the mechanical strength is preferably 0.8 to 5 cN / dtex at 90 ℃ in order to improve the mechanical properties of the high temperature in terms of mechanical properties, and to increase the yarn during drying or to improve the durability of the product under a high temperature atmosphere. More preferably, the strength at 90 ° C. is 1.3 cN / dtex or more, and most preferably 1.5 cN / dtex or more.

In addition, the polylactic acid fiber preferably has a creep rate of 1 to 15% at 90 ° C., which may further improve dimensional stability at high temperature. The creep rate at 90 ° C. can be obtained by performing a tensile test of the fiber at 90 ° C. and reading the elongation of the stress 0.7 cN / dtex in the elongation curve. More preferably, the creep rate at 90 ° C. is preferably 10% or less, and most preferably 6% or less.

On the other hand, the present invention is a method for producing a shell-core integral polylactic acid fiber,

It is composed of two parts of thermoplastic polymer resin and polylactic acid in the outer part and melt-spun through spinneret, 20 ~ 40% by weight of polylactic acid and 60 ~ 80% by weight of thermoplastic polymer. Preparing an undrawn yarn of;

Drawing the unstretched yarn melt-spun in the above step by using a first take-up roller and a second take-up roller; And

Heat treating the two-stretched fibers to produce shell-core integral polylactic acid fibers;

To prepare a shell-core integral polylactic acid fiber in a method comprising a.

At this time, in the melt spinning step, the melting temperature is preferably 220 ~ 250 ℃, if the spinning temperature is lower than 220 ℃ or higher than 250 ℃ to increase the instability of the spinning process is not properly spinning. Most preferably, the melting temperature is 230 to 240 ° C. The spinning speed is preferably 4000 to 5000 m / min, and when it is lower than 4000 m / min, the economic efficiency is lowered. There is a problem that the appearance unevenness of the product is increased.

The non-drawn yarn prepared in the above step is stretched to 1.5 ~ 3.0 times the draw ratio of the non-drawn yarn. If the draw ratio is higher than 3.0 times, mechanical property degradation due to excessive stretching may occur. In addition, when the draw ratio is lower than 1.5 times, there is a disadvantage in that the yield of the final product due to low draw is lowered.

The stretched fiber can be controlled after the heat treatment to control the crystallinity, wherein the heat treatment is preferably performed for about 5 to 10 minutes at a temperature of 110 ~ 150 ℃. If the heat treatment temperature is lower than 110 ℃ low crystallinity density improvement does not significantly affect the strength improvement, if the heat treatment temperature higher than 150 ℃ may cause the melting of some fibers due to excessive external heat. Most preferably, heat treatment at a temperature of 125 ~ 130 ℃.

The polylactic acid fiber produced by the above method significantly improves the high temperature dynamics characteristics, thereby solving the problem of durability under the manufacturing process or high temperature atmosphere, and greatly expands the development of the polylactic acid fiber. Various applications of polylactic acid fibers include, for example, yarns for crimping, such as bitumen processing, fabrics such as shirts, blouses, and pants, as well as textile materials such as cups and pads, and interiors such as curtains, carpets, mats, and furniture. It is used for interior materials of cars, belts, nets, ropes, heavy fabrics, bags, sewing materials, and other industrial materials. It can also be used for felt, nonwoven fabrics, filters, and artificial turf.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited by the following Examples.

Example 1

20 wt% of L-type polylactic acid having an optical purity of 99% and 80 wt% of a polypropylene material having a weight average molecular weight of 200,000 at a weight average molecular weight of 190,000 were dried and melt spun at 240 ° C. At this time, the spinneret hole structure is a structure in which the polypropylene melt resin flows down, and a core is a structure in which the polylactic acid melt flows down. After the fiber of the shell-core form was spun, the yarn was cooled and solidified with a cooling air at 25 ° C. After acquiring the first non-heating roller, the non-heated yarn was wound around the second non-heating roller to produce polylactic acid fiber. The polylactic acid fiber produced was 0.9 cN / dtex result through a tensile test at 90 ℃.

[Example 2]

40% by weight of L-type polylactic acid having an optical purity of 99% and a weight average molecular weight of 190,000 and 60% by weight of polypropylene material having a weight average molecular weight of 200,000 were carried out in the same manner as in Example 1, but the draw ratio was 2.5. The undrawn yarn was wound in the state and heat-treated at a temperature of 130 ° C. to prepare a fiber in the form of a shell-core. As a result, the polylactic acid fiber had a 1.0 cN / dtex result through a tensile test at 90 ℃.

Comparative Example 1

Fibers were prepared in the same manner as in Example 1, 20% by weight of polylactic acid having an optical purity of 99% and 80% by weight of polypropylene material having a weight average molecular weight of 200,000 at a weight average molecular weight of 150,000. As a result, the produced fiber was 0.8 cN / dtex result was obtained through a tensile test at 90 ℃.

Comparative Example 2

100% by weight of polylactic acid having an optical purity of 99% at a weight average molecular weight of 150,000 was carried out in the same manner as in Example 2, except that the stretched fiber was heat-treated at 125 ° C., and the fiber was formed in a single core form instead of the shell-core part. Prepared. As a result, 0.2 cN / dtex result was obtained through the tensile test at 90 ° C.

[Comparative Example 3]

100% by weight of a polypropylene material having a weight average molecular weight of 200,000 levels was prepared in the same manner as in Example 1, but in the form of a single sheath instead of the sheath-core part. As a result, the produced fiber was obtained 0.7 cN / dtex through a tensile test at 90 ℃.

division Example (% by weight) Comparative example (% by weight) Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 shape Jacket / Core Jacket / Core Jacket / Core Core alone Shell Material
Configuration A 20 40 20 100 - B 80 60 80 - 100 Processing
Condition C 2.0 2.5 2.0 2.5 2.0 D 125 ^o C 130 ^o C 125 ^o C 125 ^o C 125 ^o C A: L-type polylactic acid [Nature Works, USA]
B: Polypropylene (Honam Petroleum, Korea)
C: draw ratio
D: Treatment temperature after stretching

[Experimental Example]

In order to measure the thermal properties and the viscosity of the material according to Examples 1 to 2 and Comparative Examples 1 to 3, the measurement method was analyzed by the following method.

(1) Weight average molecular weight of polylactic acid

The sample was mixed with THF (tetrahydrofuran) in a chloroform solution to obtain a measurement solution. This was measured at 25 degreeC using the gel permeation chromatography (GPC) Waters2690 by Waters, and the weight average molecular weight was calculated | required in polystyrene conversion.

(2) strength and elongation at 25 ° C

At 25 ° C, the initial sample length was 200 mm, the tensile velocity was 200 mm / min, and the load-elongation curve was determined under the conditions shown in JIS L1013. Next, the elongation curve was obtained by dividing the load value at break by the initial fineness, making it the strength, and dividing the elongation at break by the initial sample length as the elongation.

(3) strength at 90 ° C

The elongation curve was calculated | required similarly to the measurement of the intensity | strength at 25 degreeC by the measurement temperature of 90 degreeC, and the load value was divided into the initial fineness, and it was set as the intensity | strength at 90 degreeC.

(4) Creep Rate at 90 ° C

In the elongation curve at 90 degreeC calculated | required in said (3), elongation under 0.7 cN / dtex stress was read, and it was set as the creep rate at 90 degreeC.

As a result, as shown in the following Table 2, in the case of Examples, both the strength at 90 ° C and the creep rate at 90 ° C satisfy the industrial requirements.

division Strength at 90 ° C (cN / dtex) Creep Rate at 90 ° C
(%) Example 1 0.9 15 Example 2 1.0 14 Comparative Example 1 0.8 50 Comparative Example 2 0.2 50 Comparative Example 3 0.7 30

Therefore, the polylactic acid fiber obtained by the complex spinning of polypropylene resin on the outer skin and polylactic acid resin on the inner skin contains biomass-derived materials and mechanical properties contain petroleum-based materials such as polyester. It was confirmed that.

Claims (12)

Outer shell-core integral poly, characterized in that the polylactic acid as the core and the thermoplastic polymer wraps the core in the form of an outer shell, the polylactic acid is 20 to 40% by weight and the thermoplastic polymer is 60 to 80% by weight. Lactic fiber. The shell-core monolithic polylactic acid fiber according to claim 1, wherein the polylactic acid is fermented and synthesized from biomass. The shell-core integral polylactic acid fiber of claim 1, wherein the polylactic acid is polylactic acid (PLLA), polyDlactic acid (PDLA), or mixtures thereof. The shell-core integrated polylactic acid fiber according to claim 1, wherein the thermoplastic polymer is at least one selected from polypropylene, polyethylene, polyester, polyamide, polycarbonate, styrene, and polyolefin. The shell-core integrated polylactic acid fiber according to claim 1, wherein the polylactic acid fiber has a molecular weight of 50,000 to 500,000 g / mol. The shell-core integrated polylactic acid fiber according to claim 1, wherein the polylactic acid fiber has a mechanical strength of 0.8 to 5 cN / dtex at 90 ° C. The shell-core integrated polylactic acid fiber according to claim 1, wherein the creep rate of the polylactic acid fiber is 1 to 15% at 90 ° C. A method of making a sheath-core integral polylactic acid fiber,
It is composed of two parts of thermoplastic polymer resin and polylactic acid in the outer part and melt-spun through spinneret, 20 ~ 40% by weight of polylactic acid and 60 ~ 80% by weight of thermoplastic polymer. Preparing an undrawn yarn of;
Drawing the unstretched yarn melt-spun in the above step by using a first take-up roller and a second take-up roller; And
Heat treating the two-stretched fibers to produce shell-core integral polylactic acid fibers;
Shell-core integrated polylactic acid fiber manufacturing method comprising a. 10. The method of claim 8, wherein the melting temperature in the melt spinning step is 220 ~ 250 ℃. 9. The method according to claim 8, wherein the spinning speed in the melt spinning step is 4000 to 5000 m / min. The method of claim 8, wherein the draw ratio in the two-stage stretching step is 1.5 to 3 times that of the non-stretched yarn. 10. The method of claim 8, wherein the heat treatment temperature in the polylactic acid fiber manufacturing step is 110 ~ 150 ℃.

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