Nonwoven fabric, method for manufacturing nonwoven fabric, and articles

Abstract

Nonwoven fabrics, methods for manufacturing nonwoven fabrics, and articles are disclosed. The disclosed nonwoven fabrics are subjected to 500 sec in accordance with ASTM D4440-08. -1 The shear rate and melt viscosity measured at a temperature of 230°C are 700-800 poise.

Description

[Technical Field]

[0001] The present invention relates to nonwoven fabrics, methods for manufacturing nonwoven fabrics, and articles, and more particularly to biodegradable nonwoven fabrics, methods for manufacturing nonwoven fabrics, and articles that are low in weight yet excellent in both bonding properties and strength. [Background technology]

[0002] Nonwoven fabrics are used in a wide variety of applications, including medical, industrial, protective clothing, and masks, as well as sanitary products such as diapers and sanitary napkins.

[0003] Furthermore, nonwoven fabrics are typically manufactured and used in a multilayer structure with two or more layers bonded together, and are required to have excellent strength in most applications. Therefore, many researchers are currently engrossed in developing multilayer nonwoven fabrics with superior strength.

[0004] Furthermore, in pursuit of reducing the weight of existing nonwoven fabrics, which is a recent trend, there were process and equipment limitations in maintaining the physical properties of existing nonwoven fabrics, or even in further improving those properties. [Overview of the project] [Problems that the invention aims to solve]

[0005] One embodiment of the present invention is to provide a biodegradable nonwoven fabric that is low in weight yet possesses excellent bonding properties and strength.

[0006] Another embodiment of the present invention is to provide a method for manufacturing the nonwoven fabric.

[0007] A further embodiment of the present invention is to provide an article comprising the nonwoven fabric. [Means for solving the problem]

[0008] One aspect of the present invention is, According to ASTM D4440-08, 500 sec -1 The present invention provides a nonwoven fabric having a shear rate and a melt viscosity of 700-800 poise measured at a temperature of 230°C.

[0009] The nonwoven fabric contains core-sheath type composite fibers, which may include a core portion having a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 10 to 45 g / 10 min as measured according to ASTM D1238, and a sheath portion having a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 60 to 95 g / 10 min as measured according to ASTM D1238.

[0010] The core and sheath portions of the aforementioned core-sheath composite fiber may each contain a first polylactic acid (PLA1) and a second polylactic acid (PLA2), respectively, which have different melting indices.

[0011] The melting index of the sheath portion may be 20 to 80 g / 10 min higher than that of the core portion.

[0012] The weight ratio of the core to the sheath can be between 10:90 and 50:50.

[0013] The core portion may contain a first polylactic acid (PLA1), and the sheath portion may contain a second polylactic acid (PLA2).

[0014] The aforementioned nonwoven fabric may have a toughness of 1.0 to 2.5, as expressed by the following formula 1. Formula 1: Toughness = MD Tensile Strength × MD Tensile Elongation / Base Weight

[0015] The nonwoven fabric may have a semi-crystallization time (t1 / 2) of 500 seconds or less.

[0016] The aforementioned nonwoven fabric may be a spunbond nonwoven fabric.

[0017] The nonwoven fabric may consist of two or more layers.

[0018] Another aspect of the present invention is a method for manufacturing the non-woven fabric, comprising: forming a core-forming melt and a sheath-forming melt by melting polylactic acid (PLA) for core formation and polylactic acid (PLA) for sheath formation in separate extruders respectively (step S10); releasing composite long fibers by discharging each of the melts through a spinneret having a composite spinning nozzle (step S20); cooling and stretching the released composite long fibers (step S30); collecting the cooled and stretched composite long fibers on a collecting belt and depositing them to a predetermined thickness to form a non-woven fabric (step S40), wherein, in step S20, the temperature of the spinneret is maintained at 220 to 255°C. A method for manufacturing a non-woven fabric is provided.

[0019] The method for manufacturing the non-woven fabric may further include a step (S50) of imparting mechanical physical properties to the non-woven fabric formed in step S40.

[0020] Still another aspect of the present invention is providing an article including the non-woven fabric.

Advantages of the Invention

[0021] The non-woven fabric and the article including the same according to an embodiment of the present invention have the advantages of being excellent in both bonding property and strength while being lightweight and biodegradable.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view of a core-sheath type composite fiber constituting a non-woven fabric according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view of a side-by-side type composite fiber constituting a non-woven fabric according to Comparative Example 11.

Modes for Carrying Out the Invention

[0023] The following describes in detail a nonwoven fabric according to one embodiment of the present invention.

[0024] In this specification, "half-crystallization time (t1 / 2)" refers to the time at which the degree of crystallization becomes 50% of the relative crystallization, and can be expressed by the following formula 1. Formula 1: Half crystallization time (t1 / 2)=[ln2 / k] 1 / n

[0025] In the above equation 1, ln is the natural logarithm, k is the crystallization rate parameter of the sample, and n is the Avrami parameter of the Avrami equation (n=1, 2, or 3), where n=1 means one-dimensional crystal growth, n=2 means two-dimensional crystal growth, and n=3 means three-dimensional crystal growth.

[0026] A nonwoven fabric (i.e., a core-sheath type composite fiber) according to one embodiment of the present invention is subjected to 500 sec according to ASTM D4440-08. -1 The shear rate and melt viscosity measured at a temperature of 230°C can be 700-800 poise.

[0027] If the melt viscosity of the nonwoven fabric is within the range described above, the nonwoven fabric may have excellent bonding properties and strength.

[0028] Furthermore, if the melt viscosity of the nonwoven fabric is less than 700 poise, the strength of the individual fibers constituting the nonwoven fabric decreases, and the strength of the nonwoven fabric also decreases. Also, if the melt viscosity of the nonwoven fabric exceeds 800 poise, the bonding properties of the individual fibers constituting the nonwoven fabric decrease, the bonding force between the individual fibers weakens, and as a result, the strength of the nonwoven fabric manufactured by laminating the individual fibers also decreases.

[0029] The melt viscosity of the nonwoven fabric can be determined by the structure of the fibers constituting the nonwoven fabric, the type of raw materials constituting the fibers, the proportion and physical properties of the raw materials, the manufacturing conditions and method of the fibers, and the manufacturing conditions and method of the nonwoven fabric using the fibers.

[0030] The nonwoven fabric may contain core-sheath type composite fibers.

[0031] The core-sheath type composite fiber may include a core portion with a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 10 to 45 g / 10 min, as measured according to ASTM D1238, and a sheath portion with a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 60 to 95 g / 10 min, as measured according to ASTM D1238. If the melting index of the core portion and the melting index of the sheath portion are within the above ranges, then, according to ASTM D4440-08, 500 sec -1 A nonwoven fabric can be obtained with a shear rate and melt viscosity measured at a temperature of 230°C of 700-800 poise, and a toughness of 1.0-2.5.

[0032] The core and sheath portions of the aforementioned core-sheath composite fiber may each contain a first polylactic acid (PLA1) and a second polylactic acid (PLA2), respectively, which have different melting indices.

[0033] Furthermore, the melting index of the sheath portion may be 20 to 80 g / 10 min higher than that of the core portion. If the melting index of the sheath portion is within the above range relative to the melting index of the core portion, then 500 sec according to ASTM D4440-08. -1 A nonwoven fabric can be obtained with a shear rate and melt viscosity measured at a temperature of 230°C of 700-800 poise, and a toughness of 1.0-2.5.

[0034] The weight ratio of the core to the sheath can be between 10:90 and 50:50. If the weight ratio of the core to the sheath is within the above range, then, according to ASTM D4440-08, 500 sec -1A nonwoven fabric can be obtained with a shear rate and melt viscosity measured at a temperature of 230°C of 700-800 poise, and a toughness of 1.0-2.5.

[0035] Figure 1 is a cross-sectional view of a core-sheath type composite fiber 100 constituting a nonwoven fabric according to one embodiment of the present invention.

[0036] Referring to Figure 1, the core-sheath type composite fiber 100 may include a core portion 110 and a sheath portion 120 configured to surround it.

[0037] The aforementioned nonwoven fabric may have a toughness of 1.0 to 2.5, as expressed by the following formula 1. Formula 1: Toughness = MD Tensile Strength × MD Tensile Elongation / Base Weight

[0038] The aforementioned nonwoven fabric (i.e., core-sheath type composite fiber) may have a semi-crystallization time (t1 / 2) of 500 seconds or less.

[0039] The aforementioned nonwoven fabric may be a spunbond nonwoven fabric.

[0040] The nonwoven fabric may consist of two or more layers. For example, the nonwoven fabric may be a nonwoven laminate.

[0041] The fineness and basic weight of the nonwoven fabric can be appropriately selected according to the application. Typically, the fineness is 1.0 to 2.5 denier, for example, 0.7 to 2.0 denier, and the basic weight is 15 to 100 g / m². 2 For example, 7-30 g / m 2 It is possible.

[0042] The core-sheath composite fiber may further contain additives as necessary, in addition to the first polylactic acid (PLA) and the second polylactic acid (PLA), as long as they do not impair the objectives of the present invention. The additives may include known heat stabilizers, weather stabilizers, various stabilizers, antistatic agents, antiblocking agents, anticlouding agents, fillers, dyes, pigments, natural oils, synthetic oils, waxes, or combinations thereof.

[0043] The stabilizer may include an anti-aging agent such as 2,6-di-t-butyl-4-methylphenol (BHT), a phenolic antioxidant such as tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid]methane, β-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid alkyl ester, 2,2'-oxamidobis[ethyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionic acid], a fatty acid metal salt such as zinc stearate, calcium stearate, or calcium 1,2-hydroxystearate, and a polyhydric alcohol fatty acid ester such as glycerin monostearate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, or pentaerythritol tristearate, or a combination thereof.

[0044] The filler may include silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloons, aluminum hydroxide, magnesium hydroxide, basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, talc, clay, mica, asbestos, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide, or a combination thereof.

[0045] The polylactic acid polymer described above and the additives used as needed can be mixed using known methods.

[0046] The following describes in detail a method for manufacturing a nonwoven fabric according to one embodiment of the present invention.

[0047] The method for manufacturing a non-woven fabric according to an embodiment of the present invention is the method for manufacturing the non-woven fabric described above, comprising: a step (S10) of forming a core-forming melt and a sheath-forming melt by melting polylactic acid for core formation (PLA1) and polylactic acid for sheath formation (PLA2) separately in respective extruders; a step (S20) of discharging composite long fibers by discharging each of the melts through a spinneret having a composite spinning nozzle configured to form and discharge a desired fiber structure; a step (S30) of cooling and stretching the discharged composite long fibers; and a step (S40) of collecting the cooled and stretched composite long fibers on a collecting belt and depositing them to a predetermined thickness to form a non-woven fabric.

[0048] In the step (S20), the temperature of the spinneret can be maintained at 220 to 255°C. When the temperature of the spinneret is within this range in the step (S20), a non-woven fabric having a melt viscosity of 700 to 800 poise and a toughness of 1.0 to 2.5, measured at a shear rate of 500 sec -1 and a temperature of 230°C in accordance with ASTM D4440-08 can be obtained, and good process stability (spinnability) can also be obtained in the manufacturing process of the non-woven fabric.

[0049] The step (S30) may be a step of cooling the composite long fibers discharged in the step (S20) with cooling air and further applying tension with stretching air to have a predetermined fineness.

[0050] Further, the method for manufacturing the non-woven fabric may further include a step (S50) of imparting mechanical physical properties to the non-woven fabric formed in the step (S40).

[0051] The step (S50) can be performed by means such as needle punching, water jet, ultrasonic wave, etc. as a texturing process, embossing using a heated embossing roll, or heat fusion by high-temperature ventilation.

[0052] Hereinafter, an article according to an embodiment of the present invention will be described in detail.

[0053] An article relating to one embodiment of the present invention includes the nonwoven fabric described above.

[0054] The aforementioned articles may be diapers, absorbent products, defecation products, support layers, top sheets, medical clothing, protective clothing, or masks.

[0055] The present invention will be described in more detail below with reference to examples. These examples are provided to illustrate the present invention more specifically, and the scope of the present invention is not limited to these examples.

[0056] Examples 1-10 and Comparative Examples 1-10: Production of Nonwoven Fabrics A nonwoven fabric made of core-sheath type composite fibers 100 having the structure shown in Figure 1 was manufactured by the following method. Specifically, a core-forming molten material and a sheath-forming molten material were formed by melting a first polylactic acid (PLA1) for core formation and a second polylactic acid (PLA2) for sheath formation in separate extruders. Subsequently, each of the molten materials was extruded through a spinneret having a composite spinning nozzle. Then, each of the extruded molten materials was cooled with cooling air, and tension was applied with stretching air to achieve a predetermined fineness. Subsequently, the cooled and stretched composite long fibers were collected on a collection belt and deposited to a predetermined thickness to form a nonwoven fabric. Finally, mechanical properties were imparted to the formed nonwoven fabric by embossing using a heated embossing roll.

[0057] Furthermore, the MFR of the first polylactic acid (PLA1) for forming the core, the MFR of the second polylactic acid (PLA2) for forming the sheath, the difference in MFR between the second polylactic acid (PLA2) and the first polylactic acid (PLA1), and the weight ratio of the sheath to the core are shown in Table 1 below. In Table 1 below, "manufacturing temperature of the nonwoven fabric" means the temperature of the spinneret.

[0058] Comparative Example 11: Manufacturing of Nonwoven Fabric A nonwoven fabric made of side-by-side composite fibers 1 having the structure shown in Figure 2 was manufactured by the following method. Specifically, a first polylactic acid (PLA1) for forming side A and a second polylactic acid (PLA2) for forming side B were melted in separate extruders to form molten material for side A and molten material for side B. Then, each of the molten materials was extruded through a spinneret having a composite spinning nozzle. After that, each of the extruded molten materials was cooled with cooling air, and tension was applied with stretching air to achieve a predetermined fineness. Then, the cooled and stretched composite long fibers were collected on a collection belt and deposited to a predetermined thickness to form a nonwoven fabric. After that, mechanical properties were imparted to the formed nonwoven fabric by embossing using a heated embossing roll.

[0059] Furthermore, the MFR of the first polylactic acid (PLA1) for forming side A, the MFR of the second polylactic acid (PLA2) for forming side B, the difference in MFR between the second polylactic acid (PLA2) and the first polylactic acid (PLA1), and the weight ratio of side A to side B are shown in Table 1 below. In Table 1 below, "nonwoven fabric manufacturing temperature" refers to the temperature of the spinneret.

[0060] [Table 1]

[0061] Evaluation example: Physical property evaluation of nonwoven fabrics The physical properties of the nonwoven fabrics produced in Examples 1 to 10 and Comparative Examples 1 to 11 were evaluated using the following method, and the results are shown in Table 2 below.

[0062] (1) Melt viscosity: According to ASTM D4440-08, 500 sec -1 The shear rate and melt viscosity of the nonwoven fabric were measured at a temperature of 230°C.

[0063] (2) Tensile strength: Using an Instron tensile strength meter, tensile tests were performed according to the KSK 0520 method under the conditions of a specimen width of 5 cm, spacing of 10 cm, and tensile speed of 500 mm / min, and the maximum tensile load was determined.

[0064] (3) Tensile elongation: The elongation at the time of maximum elongation measured by the method in (2) above was determined.

[0065] (4) Basic weight (weight: g / m 2 ): Measured according to ASTM D 3776-1985.

[0066] (5) Toughness: Using the tensile strength (N / 5cm) obtained in (2) above and the tensile elongation (%) obtained in (3) above, the toughness ((N / 5cm)·% / (g / m)) is calculated using the following formula 1. 2 )) was sought. Formula 1: Toughness = MD Tensile Strength × MD Tensile Elongation / Base Weight

[0067] (6) Semi-crystallization time (t1 / 2): Measured using Discovery DSC. The sample weight was 15 ± 1.0 mg, and the sample pan was an aluminum pan. The process of heating from 10°C to 300°C at a rate of 10°C / min, maintaining at 300°C for 1 minute, and cooling to 30°C was repeated twice. As a result, the Discovery DSC displayed the Tcc (cold crystallization temperature) peak and the time at which this peak appeared. The semi-crystallization time (t1 / 2) was obtained by dividing this time by 2.

[0068] (7) Process stability (spinability): During melt spinning, the movement of the filament was observed visually, and polymer drip was detected using a defect detector.

[0069] [Table 2]

[0070] Referring to Table 2 above, the nonwoven fabrics produced in Examples 1 to 10 not only had a melt viscosity in the range of 700 to 800 poise, a toughness in the range of 1.0 to 2.5, and a semi-crystallization time (t1 / 2) of 500 seconds or less, but also exhibited excellent MD tensile strength and MD tensile elongation. Furthermore, the nonwoven fabric manufacturing processes in Examples 1 to 10 were shown to have excellent process stability (spinability).

[0071] On the other hand, the nonwoven fabrics produced in Comparative Examples 1 to 11 showed that their melt viscosity was outside the range of 700 to 800 poise, their toughness was outside the range of 1.0 to 2.5, and / or their semi-crystallization time (t1 / 2) exceeded 500 seconds. Furthermore, the nonwoven fabric production processes in Comparative Examples 1 to 3 showed poor process stability (spinability).

[0072] Although the present invention has been described with reference to the drawings and embodiments, these are merely illustrative, and it will be understood by those with ordinary skill in the art that various modifications and equivalents are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical idea of ​​the appended claims. [Explanation of Symbols]

[0073] 100 Core-sheath type composite fiber 110 Core 120 Scabbard part

Claims

1. According to ASTM D4440-08, 500 sec －１ A nonwoven fabric having a shear rate and a melt viscosity of 700-800 poise measured at a temperature of 230°C.

2. The nonwoven fabric contains core-sheath type composite fibers, The nonwoven fabric according to claim 1, wherein the core-sheath composite fiber comprises a core portion having a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 10 to 45 g / 10 min as measured according to ASTM D1238, and a sheath portion having a melting index (MFR: measured at a temperature of 230°C and a load of 2.16 kg) of 60 to 95 g / 10 min as measured according to ASTM D1238.

3. The nonwoven fabric according to claim 2, wherein the core and sheath portions of the core-sheath composite fiber each contain a first polylactic acid (PLA1) and a second polylactic acid (PLA2) having different melting indices.

4. The nonwoven fabric according to claim 3, wherein the sheath portion has a melt index that is 20 to 80 g / 10 min greater than that of the core portion.

5. The nonwoven fabric according to claim 2, wherein the weight ratio of the core portion to the sheath portion is 10:90 to 50:

50.

6. The nonwoven fabric according to claim 1, wherein the toughness represented by the following formula 1 is 1.0 to 2.

5. Formula 1: Toughness = MD tensile strength × MD tensile elongation / base weight

7. The nonwoven fabric according to claim 1, wherein the semi-crystallization time (t1 / 2) is 500 seconds or less.

8. The nonwoven fabric according to claim 1, wherein the nonwoven fabric is a spunbond nonwoven fabric.

9. The nonwoven fabric according to claim 1, wherein the nonwoven fabric comprises two or more layers.

10. A method for producing a nonwoven fabric according to any one of claims 1 to 9, Step (S10) of forming a core-forming molten material and a sheath-forming molten material by melting polylactic acid (PLA) for core-forming material and polylactic acid (PLA) for sheath-forming material in separate extruders, Step (S20) involves releasing composite long fibers by extruding each of the molten materials through a spinneret having a composite spinning nozzle, Step (S30) of cooling and stretching the released composite long fibers, The step (S40) includes collecting the cooled and stretched composite long fibers on a collection belt and depositing them to a predetermined thickness to form a nonwoven fabric, A method for manufacturing a nonwoven fabric, wherein in step (S20), the temperature of the spinneret is maintained at 220 to 255°C.

11. The method for producing a nonwoven fabric according to claim 10, further comprising a step (S50) of imparting mechanical properties to the nonwoven fabric formed in the above step (S40).

12. An article comprising a nonwoven fabric according to any one of claims 1 to 9.

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