KR101427226B1 - Environmental-friendly Biodegradable Conjugate Fiber and Method of Preparing Same - Google Patents

Abstract

An environmental-friendly biodegradable conjugate fiber according to according to the present invention is a sheath-core type conjugate fiber including a sheath portion that is comprised a first polymer and a core portion that is comprised of a second polymer. The first polymer is a cellulose ester-mixed fatty acid composition including at least 1 to 10 wt% of an eco-friendly plasticizer derived from a plant. The second polymer is a polylactic acid. The cellulose ester-mixed fatty acid composition preferably has a degree of substitution of a range between 2.4 to 2.8 and a number-average molecular weight of 20,000 to 200,000. Examples of the cellulose ester-mixed fatty acid composition are cellulose acetate propionate, cellulose acetate butyrate, and a thermoplastic cellulose ester composition that is cellulose acetate. Examples of the plasticizer are epoxidized soybean oil, and a biomass-based composition such as 1,4-dianhydrosorbitol diester.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an environmentally friendly biodegradable conjugate fiber,

The present invention relates to a composite fiber comprising a cellulose derivative and poly (lactic acid) (PLA). More specifically, the present invention relates to a composite fiber produced by combining an excellent thermoplastic cellulose having improved physical properties by using an environmentally friendly plasticizer in the plasticizing process of thermoplastic cellulose and a polylactic acid having biodegradability, To a process for producing eco-friendly conjugated fibers which can be melt-spun and thus emit without using a solvent.

Conventionally, polyester, polyolefin, polyamide and the like have been widely used as synthetic fibers. However, these fibers were not decomposed when they were left in the natural environment after use, resulting in environmental problems. Therefore, it must be buried in the ground or incinerated after use. At this time, environmental burden due to air pollution and landfill has been a big problem. Accordingly, in recent years, reduction of load on the environment has been required from the viewpoint of preserving the global environment. As a result, materials that are decomposed in soil, water, and the atmosphere after use are required.

Examples of such biodegradable polymers include polysaccharides such as cellulose, cellulose derivatives, chitin and chitosan, proteins, aliphatic polyesters such as poly 3-hydroxybutyrate, polyglycolide, polylactic acid and polycaprolactone. Among them, cellulose materials and poly (lactic acid) are typical biomass materials widely available in nature, and they are attracting great attention as biodegradable materials under general environmental conditions.

Generally, the conjugated fiber can be roughly classified into a side-by-side type, a sheath-core type, and a matrix type. In the side-by-side type, two polymer compounds in a liquid state are radiated, And the matrix type is a fiber in a state of a physical mixture of different components, and the sheath-core type represents a conjugate fiber composed of a core inside the fiber and a sheath component surrounding the core.

The cellulose fiber production method is generally a wet spinning method in which a raw material is dissolved in a solvent system and a dry spinning method in which cellulose acetate is dissolved in a solvent to evaporate the solvent. For example, rayon, lyocell and the like, which are made of cellulose, are produced by a wet spinning method, and cellulose acetate is produced by a dry spinning method in which a cellulose is dissolved in a solvent to evaporate the solvent.

Examples of the thermoplastic cellulose composition capable of melt spinning and the fibers made thereof include fibers disclosed in Japanese Patent Application Laid-open Nos. 50-46921 and 62-250215, which are produced by blending cellulose acetate with low molecular weight plasticizers such as polyethylene glycol and glycerin in an amount of 50 to 59 % ≪ / RTI > by weight, to produce a cellulose composition and fibers made therefrom.

Korean Patent Publication No. 2003-88474 discloses an environmentally decomposable sheath-core type melt-spun fiber including a polylactic acid and a polyhydroxyalkanoate copolymer, and Japanese Unexamined Patent Publication No. 7-216646 And 7-133569 disclose fibers obtained by winding unstretched poly (oxyethylene) spun fibers at a speed of 1,000 m / min or less and obtaining oriented fibers in a stretching step, and Korean Patent Laid-Open No. 2001-12198 discloses a fiber having low shrinkage or high shrinkage A biodegradable polylactide fiber is disclosed.

Recently, due to environmental pollution problem, there is a need for melt spinning which does not use a special solvent or organic solvent as in the prior art, and the combined spinning of polylactic acid and cellulose is impossible through the conventional wet method and dry method.

The present inventors have developed a process for producing environmentally-friendly conjugated fibers capable of melt-spinning with good heat flowability and thus spinning without using a solvent, to produce a fiber by combining cellulose and biodegradable poly (lactic acid) It is early.

An object of the present invention is to provide a process for producing an environmentally friendly conjugated fiber which is excellent in thermal fluidity and can be melt-spun, thus emitting radiation without using a solvent.

Another object of the present invention is to provide a biodegradable conjugate fiber which is friendly to natural environment, has excellent mechanical strength for practical use, and has a lustrous luster.

The above and other objects of the present invention can be achieved by the present invention described below.

The eco-friendly biodegradable composite fiber according to the present invention is a sheath-core type conjugate fiber comprising a first polymer in a sheath portion and a second polymer in a core portion, wherein the first polymer comprises 1 to 20% by weight of an environmentally- , And the second polymer is a polylactic acid.

Preferably, the cellulose mixed composition is composed of a cellulose fatty acid mixed ester and a plasticizer, wherein the cellulose fatty acid mixed ester has an average degree of substitution in the range of 2.4 to 2.8 and a number average molecular weight of 20,000 to 200,000.

Examples of the cellulose fatty acid mixed ester include cellulose acetate propionate, cellulose acetate butyrate, thermoplastic cellulose ester composition which is cellulose acetate, and the like.

Examples of the environmentally friendly plasticizer include biomass-based compounds such as epoxidized soybean oil and 1,4-dianhydrosorbitol diester.

In the environmentally friendly biodegradable conjugate fiber according to the present invention, the ratio of the sheath / core polymer is preferably 8/2 to 2/8.

The present invention can provide a fiber which is excellent in biodegradability and can maintain excellent mechanical properties by simultaneously melt-spinning it together with a polylactic acid by adding a small amount of a specific plasticizer to the cellulose fatty acid mixed ester.

Hereinafter, the present invention will be described in detail.

The fiber of the present invention having excellent biodegradability of polylactic acid and cellulosic blend improves the mechanical strength of the conventional thermoplastic cellulose fiber despite the addition of a small amount of environmentally friendly plasticizer and has good mechanical properties And is safe against the risk of bleeding out of the plasticizer when the product is used, and can be used stably even for medical fibers.

The present invention relates to a composite fiber composed of a cellulose derivative and poly (lactic acid) (PLA). In the process of plasticizing a thermoplastic cellulose, an environmentally friendly plasticizer is used to improve the properties of the thermoplastic cellulose and biodegradability The present invention relates to a composite fiber produced by combining a polylactic acid having a polylactic acid with a polyol. The present invention also encompasses a process for producing an environmentally friendly conjugated fiber which is excellent in thermal fluidity and can be melt-spun, thus emitting radiation without using a solvent.

The eco-friendly biodegradable composite fiber according to the present invention is a sheath-core type conjugate fiber comprising a first polymer in a sheath portion and a second polymer in a core portion, wherein the first polymer comprises 1 to 20% by weight of an environmentally- , And the second polymer is polylactic acid.

Preferably, the cellulose mixed composition is composed of a cellulose fatty acid mixed ester and a plasticizer, wherein the cellulose fatty acid mixed ester has an average degree of substitution in the range of 2.4 to 2.8 and a number average molecular weight of 20,000 to 200,000. In the present invention, the cellulose mixed composition forming the outside of the composite cross-section comprises at least 80 to 99% by weight of the cellulose fatty acid mixed ester having an average substitution degree of 2.4 to 2.8 and 1 to 20% by weight of the plasticizer.

The cellulosic fatty acid mixed ester constituting the fiber comprising the cellulose mixed composition of the present invention means that three hydroxyl groups present in the cellulose glucose unit are blocked by two or more kinds of acyl groups. From the viewpoint of preparation workability and miscibility with cellulose acetate as a constituent of a different kind, the cellulose fatty acid mixed ester includes cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate hexanoate , Cellulose acetate octanoate, cellulose acetate decanoate, mixtures thereof and the like. Of these, cellulose acetate propionate contains a propionyl group other than an acetyl group, and thus has a good thermal fluidity. Cellulose acetate propionate is preferably used because it has an advantage of being able to reduce the addition amount.

The plasticizer constituting the fiber comprising the cellulose blend composition of the present invention is obtained by mixing starch extracted from corn and wheat with biomass-based 1,4-dianhydrosorbitol produced through conversion of glucose and sorbitol through enzymatic hydrolysis, Dianhydrosorbitol diester compound synthesized by combining fatty acids extracted from oil or a soybean oil compound epoxidized with soybean oil extracted from soybean oil. Based plasticizer such as phthalate esters, aromatic polycarboxylic acid esters, aromatic polycarboxylic acid esters, and lower fatty acid esters of polyhydric alcohols, which are conventional plasticizers, based on biomass. In particular, the plasticizer of the present invention has good compatibility with a cellulose fatty acid mixed ester, which is a constituent component of the thermoplastic cellulose ester composition, and exhibits a thermosetting effect capable of melt spinning.

The content of the plasticizer in the cellulose mixed composition of the present invention is preferably 1 to 20% by weight. By using the plasticizer in an amount of 1% by weight or more, the melt viscosity of the composition can be reduced, and the spinnability can be improved. On the other hand, if it exceeds 20% by weight, the thermoplastic cellulose derivative composition may have a very high thermal fluidity and melt spinning becomes difficult.

Further, the poly (lactic acid) forming the inside of the cross section in the present invention preferably has a weight average molecular weight (Mw) of 120,000 to 220,000 and a number average molecular weight (Mn) of 60,000 to 220,000. In the above range, the molecular weight has excellent spinning ability and sufficient tensile strength. On the other hand, when the molecular weight is out of the above range, the molecular weight is greatly decreased during spinning, so that sufficient tensile strength can not be obtained.

The poly (lactic acid) used in the present invention has a relative viscosity (? Rel) of 2.7 to 3.9. Relative viscosities lower than the above range lower the heat resistance of the polymer, so that sufficient strength can not be obtained. On the other hand, a relative viscosity higher than the above range raises the spinning temperature and causes heat-degradation during spinning.

Relative viscosities with low reduction ratios during spinning are suitable, and preferably have a percent reduction of relative viscosities of less than 7% in spin multifilaments. The reduction ratio of not more than 7% does not substantially cause decomposition of the polymer upon spinning, exhibits excellent radioactivity without generation of cut fibers during spinning, and exhibits particularly high tensile strength in the stretching process.

The polylactic acid used in the present invention has a melting point of 100 ° C or higher, preferably 140 ° C or higher, a melt index of 15-30 g / 10min and a melt density of 0.98-1.24 g / cm ³ (230 ° C) And should have a shrinkage of less than 8% on hot air at 130 ° C for 10 minutes.

According to the present invention, the setting of the melting temperature in the extruder of the polylactic acid in order to produce the polylactic acid-containing cross-section long fiber will melt the dried polylactic acid at a temperature of Tm + 80 to + 120 ° C , "Tm" is the melting point of the polymer). The thermoplastic cellulose fatty acid mixed ester resin constituting the sheath of the composite cross section is melted in the range of Tm +60 to + 100 ° C in the other extruder. Each polymer is fed through a spin pump that feeds the melt into a spinning beam and is sent to a pack contained within the spinning block, which filters the molten polymer in the pack and is ejected from the spinneret to form a fiber yarn.

In this case, the polylactic acid forms strength and biodegradability by the inner side of the cross section, and the cellulose mixed composition resin is located outside and forms the inherent properties of hygroscopicity, flexibility and gloss.

The released fiber yarn is once cooled and solidified by a cooling device, emulsified through a lubricating device, taken in by a first godet roller, wound around a second godet roller in a winder, and wound up.

The odd number of cans used for each emission may be a desired number of filaments or a natural number thereof. If the number of the odd number is too large, uniform cooling may not be performed, and the number of odd number is preferably 1,000 or less. The aperture diameter may be appropriately selected depending on the melt viscosity and the radiation draft of the polymer, but 0.05 to 0.50 mm is suitable. If it is 0.05 mm or more, the pressure in the spinning pack can be prevented from increasing abnormally, and if it is 0.50 mm or less, the radiation draft can be lowered without lowering the spinning speed.

It is necessary that the released sludge is processed at the place of detention at 0.5 to 5 m by using the oil supply by the oil supply device. The fiber, which has been subjected to air resistance per single yarn, will be able to travel without receiving air resistance from then on. Since the mixed composition of celluloses constituting the outside of the composite yarn is different from the polyester or the polyamide and has a high melt tension and low tendency to be prepared, when the air resistivity applied to the single yarn becomes high, the radiation tension becomes very high, Since single yarn flow and yarn breakage occur, it is an important process to process multifilaments.

The spinning speed is preferably 500 m / min to 2,000 m / min. By setting the spinning speed from 500 m / min to 2,000 m / min, the spinnability can be stably secured, and fibers having excellent mechanical properties can be obtained.

The sheath-core type long fiber can be produced by the method for producing a fiber comprising the polylactic acid-cellulose mixed composition of the present invention. (U%) of the fiber wound by a worster tester manufactured by Zellweger Uster can be obtained, and the fiber fluctuation value is preferably 0.1 to 2.0%.

Examples of the environmentally friendly plasticizer include biomass-based compounds such as epoxidized soybean oil and 1,4-dianhydrosorbitol diester.

In the environmentally friendly biodegradable conjugate fiber according to the present invention, the ratio of the sheath / core polymer is preferably 8/2 to 2/8.

The present invention can provide a fiber which is excellent in biodegradability and can maintain excellent mechanical properties by simultaneously melt-spinning it together with a polylactic acid by adding a small amount of a specific plasticizer to the cellulose fatty acid mixed ester.

The cellulose mixed composition of the present invention and the conjugated fiber composed of poly (lactic acid) can be used for industrial and medical fibers, and can be suitably used as medical fibers in particular.

Hereinafter, the present invention will be described more specifically with reference to the following examples, but the scope of protection of the present invention is not limited to these examples.

Example

Example  1-7

Cellulose acetate pyrophosphonate (degree of substitution 2.7 (acetyl group average degree of substitution 0.2, propionyl group average degree of substitution 2.5), number average molecular weight 7,500) and 1,4-dianhydrosorbitol diester at the weight ratios shown in Table 1 Kneaded at 230 DEG C using a twin-screw extruder to obtain pellets.

Polylactic acid having a melting point of 160 占 폚 and MI of 35 was melted with a core extruder, and the thermoplastic cellulose mixed composition pellets were melted with a sheath extruder. The molten polymer was transferred to the inside of the polylactic acid by the distribution plate in the composite spin spin beam, and the cellulose was radially moved outward, and was radiated into the cross section shape through the nozzle to produce the filament. Table 1 shows the compositional ratios and physical properties of the fiber constituent poly (lactic acid) and cellulose.

In Examples 1-7, changes in the physical properties of the stretched yarn were observed according to the change of the charging ratio of 1,4-dianhydrosorbitol diester by changing the charging ratios of cellulose acetate propionate and 1,4-dianhydrosorbitol diester.

Comparative Example  One

In Comparative Example 1, the physical properties of the fibers were confirmed by performing a single spinning with a conventional cellulose and a plasticizer. Composition ratio and physical properties are shown in Table 1.

[Table 1]

Example  8-14

Cellulose acetate polyphosphonate (degree of substitution: 2.7 (acetyl group average degree of substitution: 0.2, propionyl group average degree of substitution: 2.5), number average molecular weight: 7.5 million) and epoxidized soybean oil were weighed out in the weight ratio shown in Table 1 And kneaded at a temperature of 230 캜 to obtain pellets.

The polylactic acid having a melting point of 160 DEG C and an MI of 35 was melted with a core extruder, and the thermoplastic thermoplastic cellulose ester derivative pellet was melted with a sheath extruder. The molten polymer was transferred to the inside of the polylactic acid by the distribution plate in the composite spin spin beam, and the cellulose was radially moved outward, and was radiated into the cross section shape through the nozzle to produce the filament. Table 2 shows the compositional ratios and physical properties of the fiber constituent poly (lactic acid) and cellulose.

Examples 8-14 confirmed changes in the physical properties of the stretched yarn by varying the feed ratio of the cellulose acetate propionate and the epoxidized soybean oil.

[Table 2]

Comparative Example  2, 3-10

In Comparative Examples 2 and 10, the physical properties of the fibers were confirmed by performing single spinning with a conventional cellulose and a plasticizer.

In addition, in Comparative Example 3-9, the same procedures as in Examples 1-7 and 8-14 were repeated except that the phthalate-based plasticizer was used, and the physical properties of the polylactic acid / cellulose ester conjugate fiber were confirmed. Table 3 shows the compositional ratios and physical properties of the fiber constituent poly (lactic acid) and cellulose at this time.

[Table 3]

As can be seen from the results of Tables 1 to 3 above, the thermoplastic cellulose fatty acid mixture fibers of Examples 1-14 showed an increase in elongation although the strength became weaker as the content of the plasticizer increased, and a composite ratio It was confirmed that the mechanical strength for practical use was improved.

As can be seen from the results of Comparative Example 3-9, it was confirmed that the effect of the 1,4-dianhydrosorbitol diester and the epoxidized soybean oil as eco-plasticizer was equivalent or superior.

In the above Examples and Comparative Examples, physical property values were measured in the following manner.

Relative Viscosity: The sample was dissolved in a mixed solvent of phenol / tetrachloroethane = 60/40 (mass ratio) at a concentration of 1 g / dL and the relative viscosity was measured at 20 ° C using a Ubberohde viscometer.

Radiation evaluation-1): Spinning was carried out for 7 days by melt spinning. The occurrence of the cut fibers was evaluated in the following three steps (A, B and C):

A: 0 times of cutting fiber occurrence for 7 days

B: 1 to 2 times of cutting fiber generation for 7 days; And

C: 7 Number of times of cutting fiber occurrence 3 times or more

Radioactive evaluation-2): The service life of the spin nozzle was measured by date when the spin nozzle was changed due to the increase of the filtration pressure during 7 consecutive days of spinning.

Radioactive evaluation-3): The generation of cut fibers in the drawing process was evaluated in the following three steps A, B and C:

A: 0 times of cutting fiber occurrence for 7 days

B: 1 to 2 times of cutting fiber generation for 7 days; And

C: 7 Number of times of cutting fiber occurrence 3 times or more

Shrinkage in boiling water: A sample of 50 cm in initial length was suspended in boiling water for 15 minutes with a weight of 200 mg suspended and dried in the air for 5 minutes. The shrinkage ratio in boiling water was determined by the following equation.

Shrinkage (%) = (length of initial sample - length of sample after shrinkage) / length of initial sample × 100

Productivity of the filaments: The overall evaluation of the filaments was carried out in three stages, A, B, and C, taking into account the evaluation of radioactivity 1, 2 and 3, and the generation of buples.

Melt Index: MI (g / 10 min): Analyzed at 210 ° C according to the method of ASTM-D-1238

Tensile Strength and Elongation: The fiber was gripped at a temperature of 20 ° C and a humidity of 65% using a Instron tensile tester under a condition of 20 cm, under an initial load of 1.0 ± 0.1 cN / tex, and then moved at a stretching rate of 100% , And the strength [g / d] of the yarn was measured while stretching the test piece until it was broken. The elongation at this time was defined as elongation [%]. The number of measurements was 5, and the average value was determined as the strength and elongation.

Scintillation fluctuation value (U%): The U value was measured by a Wester tester manufactured by Zellweger uster under the following conditions. The number of times of measurement was 5, and the average value was set as U%.

Measuring speed: 200 m / min

Measurement time: 2.5 minutes

Measuring fiber length: 500 m

Twist: S twist, 12000 / m

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (6)

A sheath-core type conjugate fiber comprising a first polymer in a sheath portion and a second polymer in a core portion, wherein the first polymer is a cellulose mixed composition comprising 1 to 20% by weight of an environmentally friendly plasticizer derived from a plant, Wherein the polymer is polylactic acid.
The cellulose ester composition according to claim 1, wherein the cellulose mixed composition is composed of a cellulose fatty acid mixed ester and a plasticizer, wherein the cellulose fatty acid mixed ester has an average degree of substitution in the range of 2.4 to 2.8 and a number average molecular weight of 20,000 to 200,000 Environmentally friendly biodegradable conjugated fiber.
The method of claim 2, wherein the cellulose fatty acid mixed ester is selected from the group consisting of cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate propionate butyrate, cellulose acetate hexanoate, cellulose acetate octanoate, cellulose acetate decanoate, And a mixture thereof.
The environmentally friendly biodegradable conjugate fiber according to claim 1, wherein the environmentally friendly plasticizer is an epoxidized soybean oil or 1,4-dianhydrosorbitol diester.
The environmentally friendly biodegradable composite fiber according to claim 1, wherein the ratio of the sheath / core polymer is 8/2 to 2/8.
A method for producing a sheath-core type conjugate fiber comprising a first polymer in a sheath portion and a second polymer in a core portion, the method comprising: mixing at least 1 to 20 wt% of an environmentally- And the second polymer is melt-spinning a raw material component which is a poly (lactic acid). The method for producing an environmentally friendly biodegradable conjugate fiber according to claim 1,