KR20040078351A - Thermally Bondable Non-circular Conjugate yarn and absorptive non-woven produced therefrom - Google Patents

Abstract

PURPOSE: A conjugate fiber prepared by conjugate spinning of a section of a sheath part in the shape of a circle and a section of a core part in the shape of a modified cross-section while using a low melting point polymer at the sheath part and a high melting point polymer at the core part is provided. An absorbent nonwoven fabric prepared from the conjugate fiber provides thermal binding properties and has good feel, absorbency and strength and is thus used for sanitary products. CONSTITUTION: The conjugate fiber consists of a core part(1) comprising a high melting point polymer and a sheath part(2) comprising a low melting point polymer surrounding the core part. The high melting point polymer is selected from the group consisting of polypropylene or polyethylene terephthalate, and the low melting point polymer is polyethylene. The sheath part is in the shape of a circle, and the core part is in the shape of 3 to 6 radial branches. The absorbent nonwoven fabric is prepared by heat treatment of the conjugate fiber.

Description

Thermobonded Non-woven Composite Fiber and Absorptive Non-woven Produced Therefrom

Composite spun fiber having a low melting point polymer as a cis component and a high melting point polymer as a core component can be manufactured as a nonwoven fabric having excellent touch and strength, and thus is used as a main material for diaper and sanitary napkin manufacturing. Such heat-adhesive composite fibers are made of polyethylene (hereinafter referred to as PE) / polypropylene (hereinafter referred to as PP) (JP-A-52-37097), PE / polyethylene terephthalate (hereinafter referred to as PET) (JP-A 3-21648), copolymerization PP / PP (Japanese Special Employment Office 55-26203) is shown. Composite fibers having such a sheath-core structure have characteristics of imparting adhesive performance by heat processing and pressing without using a chemical adhesive in the manufacture of nonwoven fabrics, and thus are used as physiological products requiring general hygiene. As living standards increase in recent years, there is a demand for better nonwoven fabric properties that can provide consumers with a refreshing feel.

Nonwoven fabrics used for sanitary napkins and baby diapers can improve the refreshing sensation by fast moisture absorption. In order to improve water absorption, various hydrophilic agents can be used for the fibers. The hydrophilic agent is a method of using an alkyl sulfonate (R-SO ₃ Na) salt is shown in Japanese Patent Application Laid-Open No. 5-272013. However, the case where the water absorption is improved by improving the physical property of the fiber itself without using a chemical treatment method is limited. Fibers having a circular cross section used in nonwoven fabrics have limitations in improving water absorption. Therefore, in order to improve water absorption, it is effective to use fibers having a cross-sectional shape.

The fiber cross-sectional structures shown in Japanese Patent Laid-Open No. 5-321018 suggest a fiber cross-sectional structure enabling a plurality of divided structures. The cross-sectional structures of Japanese Patent Laid-Open No. 5-321018 provide fibers that can have a heteromorphic cross-sectional shape by providing good splitting through processes such as needle punching or water jet. However, the split fiber is not applicable to a method capable of securing the bonding force of the nonwoven fabric by thermal bonding.

The fiber cross-sectional structure of Japanese Patent Laid-Open No. 11-323663 suggested a spinning technique for producing a hetero-section composite fiber. Fibers produced by the fiber cross-section shown in Japanese Patent Laid-Open No. 11-323663 impart a deformed cross-sectional shape in the spinning step, so that trimming can easily occur due to severe friction between fibers in the fiber manufacturing process, and carding work even when manufacturing nonwoven fabrics. In addition, the connection between the high melting point portion and the low melting point portion shows a fundamentally unstable structure and is easily separated in advance by an external physical impact, and the area of the low melting point portion connected to the high melting point portion is very small when heat-treated. Since the thermal fusion effect is lowered, there is a problem that the adhesive strength does not come out as high as expected.

In order to solve the above-mentioned problems of the related art, the present invention provides a composite spinning fiber having a low melting point polymer as a first component as a sheath and a high melting point polymer as a core as a second component. In addition, the core cross-section is a composite cross-section in the form of a cross-sectional shape to preserve the circular cross-sectional shape in the fiber manufacturing step, to provide a composite spinning fiber that smoothly solves the workability problems from the fiber manufacturing process to the nonwoven fabric manufacturing process It is done.

In addition, the present invention, when the non-woven fabric using the composite spun fiber prepared by the present invention after the heat treatment for heat bonding to melt the low melting point portion of the sheath portion similar to the core portion having a high melting point in the form of a cross section It is an object of the present invention to provide a nonwoven fabric having excellent absorptivity due to the deformed shape of the sheath portion and capillary action of the release cross section.

It is an object of the present invention to provide a nonwoven fabric having a higher hydrophilicity and excellent water absorption by using a small amount of a hydrophilic chemical oil agent.

An object of the present invention is to provide a nonwoven fabric by thermal bonding of composite spun fiber suitable for the use of sanitary products requiring hygiene by imparting adhesive performance without using a chemical adhesive.

An object of the present invention is to improve the thermal adhesiveness after fabrication of nonwoven fabric by solving the weakness of the structural coupling between the high melting point portion and the low melting point portion of the conventional composite spun release cross-sectional structure.

1 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Example 1 of the present invention.

2 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Example 2 of the present invention.

3 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Example 3 of the present invention.

4 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Comparative Example 1.

5 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Comparative Example 2.

6 is a cross-sectional view before heat treatment of a release cross-section composite fiber according to Comparative Example 3.

Figure 7 is a cross-sectional view after heat treatment of the release cross-section composite fiber according to Example 1 of the present invention.

* Code descriptions for the main parts of the drawings

1: core part 2: sheath part

3: radial branches

In order to achieve the above technical problem, the present invention is a sheath core type heat-adhesive composite spun fiber composed of a core part made of a polymer having a high melting point component and a sheath part made of a polymer having a low melting point component surrounding the core part. The cross-sectional shape is circular, and the cross section of the core portion is provided with a heat-adhesive release cross-section composite fiber made of a release cross-section having a plurality of radial branches.

Typically, the low melting point polymer refers to a polymer that can be melted at a processing condition of 120 to 140 ° C., and the high melting point polymer refers to a polymer that is not melted at a temperature of 160 ° C. or lower, and the heat-adhesive release cross-section composite of the present invention. Polyethylene may be used as the polymer of the low melting point component of the sheath portion of the fiber, and polypropylene or polyethylene terephthalate may be used as the high melting point component of the core portion. The core part of the composite fiber of the present invention has a release cross section in which a plurality of radial branches are formed from the center of the core part toward the sheath part. It is preferable that three to six such radial branches are formed.

The present invention provides an absorbent nonwoven fabric which is made by thermally bonding a heat-bonded release cross-section composite fiber prepared as described above. The absorptive nonwoven fabric of the present invention melts the sheath portion of the heat-adhesive release cross-section composite fiber by heat treatment, thereby deforming the shape of the composite fiber into the shape of the release cross-section, thereby widening the surface area and improving absorbency. The heat treatment process for producing the absorbent nonwoven fabric can be made using an air-through bonding method at an air temperature of 130 ℃ to 160 ℃. In one embodiment of the present invention, since the melting point of PE used as the low melting point component is about 130 ° C., the melting point of PE is not lowered at 130 ° C. or lower, and thus the melting point of PP used as the high melting point component is 160 ° C. Therefore, when the temperature is 160 ° C or higher, PP, which is a high melting point component, is melted and the strength of the nonwoven fabric is lowered and the shape is deformed. Therefore, the heat treatment is preferably performed at a temperature of 130 ° C to 160 ° C. The bonding method is particularly effective when the air through method is used, and heat treatment can be performed even with the TB (Thermal Bonding) method.

Typically, the hydrophilic emulsion has a fiber emulsion adhesion ratio of about 0.4 to 0.6% in order to improve the absorbency of the nonwoven fabric. However, in the present invention, a fiber having a small amount of fiber emulsion adhesion ratio of about 0.2% is used to further improve human affinity. It can be seen from the examples that even when a nonwoven fabric is manufactured, it is possible to maintain excellent absorbency of the nonwoven fabric. This is because the shape of the sheath is deformed in a form similar to that of the core in the form of a cross section, so that the absorbency of the nonwoven fabric can be improved by the capillary action of the cross section.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a circular cross-sectional shape of the sheath portion as described above in the present invention, and at the same time the core portion is composed of a cross-sectional shape of the triangular leg is a complex spinning, but the region of the heteromorphic cross-section is necessarily present in the circular cross-sectional area of the sheath portion The form is shown.

2 to 3 are designed with the same concept as that of FIG. 1, and have a heteromorphic cross-sectional shape of the core portion and a different number of radial branches of the core portion.

4 is a cross-sectional structure of a composite yarn having a conventional sheath core shape, wherein the sheath and the core portion have a circular shape at the same time.

5 is a cross-sectional structure of a composite cross-section of a heterosized cross section of a triangular leg having a conventional sheath core shape, and the hatched portion forms a low melting point polymer, and the other side is made of a high melting point polymer.

6 is a cross-sectional structure of a hetero-cross-section composite yarn having 8 radial branches in the core portion.

In the present invention, the measurement of each property and physical properties was measured by the following method.

(1) Spinning workability: Spinning workability is achieved if both ends of the fiber under detention are not less than 1 time / hour, or if the radiation drip is not normal radiation drawing by more than 1 time / hour. It was poor, and if only one of them corresponds to the middle, it was judged that the workability was good if all were good.

(2) Cross-sectional formability: When measuring by optical microscope, the fiber cross section consisting of about 20 to 30 pieces is measured three times by putting in a photograph of a certain size. It was judged that the cross-sectional formability was poor when the number of gaps having one or more gaps existed was three or more, and when one or more was present, it was evaluated as a middle one.

(3) Stretch workability: The workability was judged to be poor when at least three times of trimming occurred in the drawing process, and it was evaluated as medium when at least three times and less than three times.

(4) Crimp workability: Visually observed during the crimp formation process, when crimper entry process failed more than 5 times, it was evaluated as poor workability. The workability was evaluated as good.

(5) Cutting property: According to the optical microscopic analysis by the cutting process, it was evaluated that the cutting property was poor even when the thermal fusion caused by frictional heat occurred only once.

(6) Composite Fiber Fineness: Fineness was measured based on ASTM D1577.

(7) Fibrous emulsion adhesion rate: After sample 10g of test fiber, using SOXHLET (soxhlet), reflux extrusion of the mixed solvent of methanol / ether = 1/3 hours, and then remove the solvent to measure the residual amount.

(8) Absorption: A 10 cm long sample piece is cut from a nonwoven fabric made using the release cross-section composite fiber of the present invention, and a small amount of red aqueous ink is attached to the surface of the nonwoven fabric to visually finely observe the permeability of the ink in the nonwoven fabric. Was evaluated. When the penetration time of the ink into the nonwoven fabric was 5 seconds or more, it was determined that the absorbency was poor.

(9) Heat adhesive strength: 2.5 cm wide sample pieces were cut from a nonwoven fabric made using the release cross-section composite fiber of the present invention, and cut into a nonwoven fabric of about 20 g / cm ² made of polypropylene fiber (2 denier). The specimen piece having a width of 2.5 cm and the tip portion were overlapped by about 1 cm in length, and a pressure of 3 kg / cm ² was applied for 3 seconds, followed by thermocompression bonding at a specific temperature, and the measurement width was 10 cm using a tensile tester. Peel force of adhesive strength is measured in / min.

(10) Non-woven fabric workability: Any problem such as poor visual focusing or a lot of floating materials due to visual observation in the carding process, which is a manufacturing process of the non-woven fabric made using the release cross-section composite fiber of the present invention Even if only occurred, the workability was judged to be poor.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example 1

As shown in Table 1, the composite fiber was melt-spun so that the first component and the second component were used, and a heteromorphic cross-sectional shape as shown in FIG. 1 with three radial branches in the core part (first component) appeared. The component ratio was 50/50 for the first component and the second component. The cross-sectional ratio can be applied in various ways, but usually 50/50 is the most preferred and commercialized. If the ratio of PE as the first component is 30 or less, the thermal adhesiveness is inferior, and if it is 70 or more, the fiber strength is lowered. During spinning, the spinning temperature was maintained at 260 ° C and the cooling temperature was 20 ° C, and the winding speed was 1,000 m / min. After spinning, stretching was carried out 3.5 times with a thermal roller at 90 ° C., and mechanically crimped with a stuffing box, and cut. In order to manufacture the nonwoven fabric, the fibers were carded at a speed of 30 mpm using a roller carding machine, a nonwoven web was prepared, and the dryer was treated at an air temperature of 150 ° C. for 2 minutes. At this time, the absorbance was measured to measure the absorption performance of the nonwoven fabric.

Example 2

Work was carried out in the same manner as in Example 1, but the cross-sectional shape was used in the form shown in Figure 2 of the number of radial branches of the core portion 4, the composite spinning ratio of the first component and the second component is 50/50 It was.

Example 3

Work was carried out in the same manner as in Example 1, the cross-sectional shape was used in the form shown in Figure 3, the first component was used polyethylene and the second component was polyethylene terephthalate using a spinning temperature of 260 ℃ The composite spinning ratio was set to 50/50. In the nonwoven fabric manufacturing process, the air temperature for thermal bonding was set at 150 ° C. for 2 minutes.

Example 4

As shown in Table 2, the composite fiber was melt-spun so that the first component and the second component were used, and a heteromorphic cross-sectional shape as shown in FIG. 2 having 4 protrusions in the core part (first component) appeared.

The discharge ratio of the first component and the second component was 40/60. During spinning, the spinning temperature was maintained at 260 ° C and the cooling temperature was 20 ° C, and the winding speed was 1,000 m / min. After spinning, stretching was carried out 3.5 times with a thermal roller at 90 ° C., and mechanically crimped with a stuffing box, and cut. In order to manufacture the nonwoven fabric, the fibers were carded at a speed of 30 mpm using a roller carding machine, a nonwoven web was prepared, and the dryer was treated for 2 minutes at an air temperature of 150 ° C. At this time, the absorbance was measured to measure the absorption performance of the nonwoven fabric.

Example 5

Work was carried out in the same manner as in Example 4, but the discharge ratio of the first component and the second component was 60/40.

Comparative Example 1

Work was carried out in the same manner as in Example 1, the cross-sectional shape was used in the form shown in Figure 4, the composite spinning ratio of the first component and the second component was 50/50.

Comparative Example 2

Work was carried out in the same manner as in Example 1, the cross-sectional shape was used in the form shown in Figure 5, the composite spinning ratio of the first component and the second component was 50/50.

Comparative Example 3

Work was carried out in the same manner as in Example 1, but the cross sectional shape was used as shown in FIG. 6, in which the number of radial branches of the core part was 8, and the ratio of the combined radiation of the first component and the second component was 50/50. It was made.

Comparative Example 4

The operation was carried out in the same manner as in Example 4, but the ratio of the composite radiant discharge of the first component and the second component was 20/80.

Comparative Example 5

Work was carried out in the same manner as in Example 4, but the ratio of the composite spinning discharge of the first component and the second component was 80/20.

Table 1 and Table 2 show the results of Examples and Comparative Examples.

Thermal Bond Strength: Measured by thermal bonding with a polypropylene spunbond nonwoven fabric (40 g / cm ² ).

Q = A1 / A2 = fiber cross-sectional area ratio, where A1 is the area of the core portion of the fiber cross section, and A2 is the total area including the sheath portion and the core portion of the fiber cross section.

The calculation method of the fiber cross-sectional area ratio Q is useful because it is possible to calculate the cross-sectional area ratio with only the discharge ratio in the spinneret and the density of the melting point polymer and the low melting point polymer without directly measuring the area ratio of the fiber cross section.

As can be seen in Tables 1 and 2, the cross-sectional composite fiber according to the present invention has a sheath portion exhibiting a circular shape, and excellent workability from fiber manufacturing to nonwoven fabric production, and at the same time, excellent fiber between nonwoven fabrics by heat treatment during nonwoven fabric production. It is possible to produce non-woven fabrics with improved water absorption compared to conventional sheath-core heat-bonded nonwoven products by the channel effect formed on the fiber surface by modifying the shape of the core part that can be heat-bonded and has a low melting point. Make it possible. As in Comparative Example 3, when the number of radial branches of the core part is as large as eight, the absorbency, that is, the absorbency deteriorates because the sheath part is close to the circular shape even when the sheath part deforms according to the shape of the core part during heat treatment. Therefore, the core part according to the present invention preferably has three to six radial branches. In addition, when the ratio of the area of the core portion to the total area of the fiber cross section exceeds 80%, the thermal bonding effect is lowered. If the ratio falls below 20%, the strength of the fiber is lowered, so the nonwoven fabric strength is lowered.

As described above, the present invention provides a composite spun fiber having a low melting point polymer as the first component and a high melting point polymer as the core component, wherein the cross section of the core portion is in the shape of a heteromorphic cross section and the cross section of the sheath portion completely surrounds the core portion. In the fiber manufacturing step in the form of composite spinning in a circular shape, the shape of the circular cross section is preserved, and thus the workability from the fiber production to the nonwoven fabric manufacturing process is superior to that of the composite spun fiber having a heteromorphic cross section.

In addition, the present invention, when the non-woven fabric using the composite spun fiber prepared by the present invention after the heat treatment for heat bonding to melt the low melting point portion of the sheath portion similar to the core portion having a high melting point in the form of a cross section Since the shape of the sheath portion is deformed, even when human-friendly fibers having a low fiber emulsion adhesion rate of the hydrophilic emulsion are used, there is an effect that the nonwoven fabric has excellent absorbency due to the capillary action of the cross section.

The nonwoven fabric of the present invention is suitable for the use of sanitary articles requiring hygiene by imparting adhesive performance by thermal bonding without using a chemical adhesive.

In addition, the present invention improves the thermal adhesiveness after manufacturing the nonwoven fabric by solving the weakness of the structural coupling between the high melting point portion and the low melting point portion of the conventional composite spun release cross-sectional structure.

Claims (7)

A sheath-core type heat-adhesive cross-section composite fiber composed of a core part made of a polymer having a high melting point component and a sheath made of a polymer having a low melting point component surrounding the core part, The high melting point component of the core portion is a polymer selected from the group consisting of polypropylene (PP) or polyethylene terephthalate (PET), The low melting point component of the sheath portion is polyethylene (PE), The cross-sectional shape of the sheath portion is circular, The cross section of the core portion is characterized in that formed in the form of a cross-section having a plurality of radial branches, heat-sensitive release cross-section composite fiber. According to claim 1, wherein the radial branches of the core portion, characterized in that three to six, heat-adhesive release cross-section composite fiber. The thermally adhesive release cross-section composite fiber according to claim 1, wherein the core portion occupies 30% to 70% of the total fiber cross-sectional area. 4. The heat-adhesive cross-section composite fiber according to claim 3, wherein the core portion occupies 50% of the total fiber cross-sectional area. An absorbent nonwoven fabric made by heat-treating the heat-adhesive release cross-section composite fiber of claim 1. 6. The absorbent nonwoven fabric of claim 5, wherein the sheath portion of the heat-adhesive release cross-section composite fiber is melted by the heat treatment to deform the shape of the composite fiber into a shape of a cross-sectional cross-section, thereby improving absorbency. Non-woven. The absorbent nonwoven fabric as claimed in claim 5, wherein the heat treatment is performed using an air-through bonding method at an air temperature of 120 ° C to 160 ° C.