JPH05272013A - Hydrophilic polyolefinic conjugate fiber - Google Patents

Abstract

PURPOSE:To enable not only a polyethylenic part but also a polypropylene part itself to have sufficient hydrophilicity in the surface of polyolefinic conjugate fiber and prevent undesirable effects of smoking on producing them. CONSTITUTION:The objective hydrophilic polyolefinic fiber is produced by including Na salt of an alkylsulfonate in an amount of 0.5-5wt.% based the total amount of the Na salt of the alkylsulfonate and a surface-forming component in the surface-forming component of the conjugate fiber composed of polypropylene and polyethylene. Since the surface of the hydrophilic polyolefinic fiber of this invention has sufficiently lasting hydrophilicity even in a polypropylene part, the polyolefinic fiber can be formed into a nonwoven fabric and used as materials characterized by crimpability and heat bonding properties for applications of a skin material such as a paper diaper. The skin material is capable of always rapidly passing urine, etc., therethrough without causing disorders such as contact dermatitis. Since the conjugate fiber can be produced in a good environment without smoking, the production can be increased to further extend uses as the skin material for disposable sanitary materials such as the paper diaper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrophilic polyolefin composite fiber composed of two kinds of polymers containing propylene and ethylene as main monomer components.

[0002]

2. Description of the Related Art Fibers produced from polypropylene or polyethylene (hereinafter, referred to as "polyolefin" as a general term for polyolefins) containing propylene or ethylene as a main monomer component, so-called polypropylene fibers and polyethylene fibers, are used in various applications. It is used a lot,
It is also widely used as a raw material fiber for non-woven fabrics for skin materials such as disposable diapers and other disposable hygiene products. A sanitary article such as a paper diaper is composed of an epidermis material that comes into contact with the skin and an absorbent material thereunder, and urine or the like passes through the epidermis material and is absorbed by the absorbent material. The basic requirement that such a sanitary article should have is that it does not cause rash, swelling, or other problems due to discharged urine or the like. Problems such as a rash occur when the discharged urine or the like is not completely absorbed by the absorbent and remains on the surface of the skin material. Therefore, in order to eliminate such obstacles, it is important that almost no urine or the like passes through the skin material promptly, and for that reason, urine or the like easily penetrates between the fibers of the skin material and passes. It is necessary to have hydrophilicity.

As raw material fibers for the above-mentioned non-woven fabric for skins, in addition to fibers having a uniform cross-section such as polypropylene fibers and polyethylene fibers, composite fibers in which polypropylene and polyethylene are arranged in a flat type or a sheath-core type are used. Was
Non-woven fabrics for skin materials, which have characteristics such as crimpability and thermal adhesiveness, have been trial-produced and used. However,
Polyolefins such as polypropylene and polyethylene are inherently hydrophobic, so composite fibers made of them (hereinafter sometimes referred to as polyophine composite fibers) are not suitable for skin material applications. Normally, an oil agent containing a surfactant as a main component is attached to the surface of the composite fiber to give it hydrophilicity during the production of the composite fiber, so that the nonwoven fabric for skin material is not subjected to treatment such as washing until commercialization. It can be used as a raw material. However, even in this case, if the oil agent component on the surface of the composite fiber is washed away by the first urination after wearing it as a paper diaper or the like, the hydrophilicity is reduced thereafter.

Further, a nonwoven fabric composed of a polyolefin composite fiber processed by a spunlace method in which a fibrous web is entangled with a high-pressure water stream is used because the oil component on the surface of the composite fiber is washed away by the water stream and loses hydrophilicity. A step of attaching an oil agent is required. Further, a nonwoven fabric composed of a polyolefin composite fiber obtained by forming a nonwoven fabric by composite spinning with a high-speed air flow by the spunbond method is not hydrophilic because it does not use an oil agent during spinning and can be used only in a limited part of the skin material. However, there is a problem in that it requires a step of attaching an oil agent.

In recent years, such a problem has been found in polyolefin-specific wetting agents (glyceride and alkoxylated phenol, or polyoxyalkylene fatty acid ester alone,
Alternatively, a proposal has been made to solve the problem by producing a fiber from a composition obtained by adding a mixture of these and making the fiber itself hydrophilic (JP-A-60-194113). However, when the composite fiber containing polypropylene and polyethylene as a composite component is made hydrophilic by the above wetting agent,
Although it exhibits sufficient hydrophilicity in the polyethylene part,
Hydrophilicity is insufficient in the polypropylene part. In addition, there was a drawback that the wetting agent generated a lot of smoke at the nozzle during the composite spinning, which reduced spinnability and deteriorated the spinning work environment.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to construct a hydrophilic polyolefin composite fiber so as to solve the above-mentioned drawbacks of the prior art.

[0007]

As a result of various studies, the present inventor has found that alkyl sulfonate Na as a compounding agent imparting hydrophilicity to at least a fiber surface forming component of a composite fiber containing polypropylene and polyethylene as a composite component. The present invention has been completed by clarifying that the above-mentioned problems can be achieved by containing at least 0.5 to 5% by weight of a salt in the fiber surface forming component. Hereinafter, the present invention will be described in detail.

The two kinds of polyolefins containing propylene and ethylene as main monomer components used in the present invention, so-called polypropylene and polyethylene, are
It is a crystalline polymer obtained by using a generally known Ziegler-Natta catalyst, and not only a homopolymer but also a small amount, for example, 0.1 to 10% by weight of α-olefin such as ethylene (in the case of polypropylene), propylene (of polyethylene). Case), butene-1 (common to both) and the like. MF of polypropylene used in the present invention
R (ASTM D1238 condition L) and polyethylene M
I (ASTM D1238 condition E) is not particularly limited, but it is preferable for spinning to use polypropylene having MFR of 5 or more and polyethylene having MI of 10 or more. In the present invention, the composite structure in which polypropylene and polyethylene are arranged as a composite component is a composite structure in which polypropylene or polyethylene alone constitutes each of two or more sections in the fiber cross section. Generally, as such a composite structure, there can be various modes in which three or more areas are arranged in parallel, concentric circles, or random seas / islands, etc., but they are typical and most practical. The two sections are arranged in a side-by-side or sheath-core arrangement, one of the two sections being made of polypropylene and the other being made of polyethylene.

In the present invention, the alkyl sulfonate Na salt is at least the fiber surface-forming component of such a composite fiber, that is, any of the composite components in the case of the parallel type, and the sheath-core type. Is contained in the sheath component. And, the content of the alkyl sulfonate Na salt is a fiber surface forming component, that is, in the case of the parallel type, the whole fiber which is a total of both components or the total thereof, or the sheath component in the case of the sheath core type
0.5 to 5% by weight based on the total amount of Specifically, in the case of the parallel type, the alkyl sulfonate N is added to both the composite components, that is, both polypropylene and polyethylene.
a is included, and the content ratio in each component is not necessarily the same. In the case of the sheath-core type, the sheath portion may be formed of polyethylene or polypropylene, but the former is often used in order to impart thermal adhesiveness. In the case of this sheath-core type, the core component which does not form the fiber surface may also contain the alkylsulfate Na salt, but it is completely unnecessary that the content is higher than that of the sheath component.

The alkyl sulfonate Na salt used in the present invention has the structure of the following formula (I). R in the _{R-SO 3 Na ··· (I} ) above formula represents an alkyl group. The C number of R is preferably 10 to 20. When the content of the alkyl sulfonate Na salt is less than 0.5% by weight, hydrophilicity is not developed to an effective degree. Further, even if the content exceeds 5% by weight, the effect of increasing the amount is hardly recognized, but the yarn breakage at the time of spinning increases, resulting in quality deterioration and manufacturing difficulty.

Additives such as various stabilizers, lubricants, pigments and radical generators such as peroxides are contained in each composite component of the hydrophilic polyolefin composite fiber according to the present invention within a range that does not impair the effects of the present invention. You can To incorporate the alkyl sulfonate Na salt into the composite fiber, a method of adding it at the time of melt spinning by supplying it at a predetermined ratio to each extruder of polypropylene or polyethylene at the time of melt spinning, or at the time of producing polypropylene or polyethylene pellets The method may be a spinning method using the pellets added in advance. A known method is generally used as the melt spinning method. For example, 2
Using a spinning machine for composite fibers consisting of an extruder of a table and a composite spinning nozzle assembly, each pellet of polypropylene and polyethylene was fed to each extruder to obtain 190 ° C-3
After melt-kneading at a temperature of 00 ° C, extrude from the composite spinning nozzle,
The extruded molten resin is taken up by a roll to first produce a composite undrawn yarn. Next, this composite undrawn yarn is drawn several times while being heated using a hot roll, a hot plate, a hot air heating furnace, etc., and crimped by a crimping device if necessary, and when it is made into short fibers, it has a predetermined length. Cut into pieces.

[0012]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples, but the present invention is not limited thereto. In addition, the measuring methods or definitions of the physical properties shown in the examples are collectively shown.

MFR: ASTM D1238 Condition L MI: ASTM D1238 Condition E Hydrophilicity: A fiber bundle is prepared to have a length of 10 cm and a weight of 6 g, and twisted 4 times. Droplets are attached, and the permeability of the ink into the fiber bundle is visually evaluated based on the following criteria. ⊚: Permeates quickly. ○: Penetrate within 5 seconds. Δ: Penetration takes 5 seconds or more. X: Does not penetrate.

Spinnability of raw material pellets: Extrusion temperature 250
Evaluation is based on the following criteria based on the number of yarn breakages per 60 minutes when spun at 0.5 ° C., extrusion rate per hole of 0.5 g / min, and spinning speed (also referred to as winding speed) of 800 m / min. ○: The thread was not broken. X: One or more thread breaks. Smoke emission of the raw material pellets: Under the same spinning conditions as the spinnability evaluation, the smoke emission at the nozzle was visually observed in comparison with the smoke emission of the raw material to which the alkyl sulfonate Na salt was not added, and evaluated based on the following criteria. To do. ◯: Smoke emission equivalent to that of no addition. Δ: Some more than not added. X: Remarkably more than no addition.

Examples 1 to 3 and Comparative Examples 1 to 3 MFR10 powdered polypropylene (homopolymer) was blended with a predetermined amount of the alkyl sulfonate Na salt having 14 carbon atoms of the alkyl group shown in Table 1. BHT (bruchylated hydroxytoluene) was added to 100 parts by weight of the mixture.
0.1 parts by weight, 0.1 parts by weight of calcium stearate were added and mixed for 1.5 minutes with a Henschel mixer, then the caliber 40m
A polypropylene pellet was obtained by melt-kneading and pelletizing at 200 ° C. using a m single-screw extruder. Further, the same amount of each of the same three kinds of additives as described above was mixed and mixed with powdered polyethylene (homopolymer) having an MI of 2.5, and pelletized in the same manner to obtain polyethylene pellets.

A composite ratio (weight ratio) of the two kinds of pellets thus obtained was obtained from a composite melt spinning machine equipped with a parallel type composite spinning nozzle assembly having 100 holes each having a hole diameter of 1 mm. Extrusion temperature of 250 ℃ extruded in 1 and melt spun at a spinning speed of 800 m / min.
An undrawn multi-composite filament consisting of 100 5.6 denier fibers was produced. In the above process, an oil agent was attached to the fiber surface to reduce friction with the guide. Then, in order to evaluate the spinnability of the composition used as the spinning raw material, the spinning time and the number of yarn breakages were counted. A part of this unstretched multi-composite filament was stretched on a hot plate heated to 100 ° C under the conditions of a final stretching speed of 60 m / min and a stretching ratio of 3 times, and it was composed of 100 fibers of 1.9 denier in a parallel type composite structure. A drawn multi-composite filament was produced. In this way, the hydrophilic polyolefin composite fiber according to the present invention and a comparative fiber (there are two types of undrawn yarn and drawn yarn for each) were obtained.

50 g of each of the unstretched and stretched multi-composite filaments was washed with water to wash off the oil component, dried with a hot air dryer at 80 ° C. for 12 hours, and then evaluated for hydrophilicity. Table 1 shows the results of the spinnability and smoke generation of the raw material pellets and the hydrophilicity of the composite fiber.

Examples 4 to 6 and Comparative Examples 4 to 6 The same as Examples 1 to 3 except that the alkyl sulfonate Na salt was not added separately from the polyethylene pellets obtained in Examples 1 to 3. Using the polypropylene pellets obtained as described above, the same composite melt spinning machine as in the case of Examples 1 to 3 was used except that a sheath core type was installed as a composite spinning nozzle assembly. The spinnability of the pellets used as the spinning raw material was the same as in Examples 1 to 3 and Comparative Examples 1 to 3 except that the polyethylene pellets constituted the sheath portion and the polypropylene constituted the core portion. In addition, the smoke emission was examined, and the hydrophilicity of the obtained sheath-core type hydrophilic polyethylene composite fiber and a comparative fiber was measured. The results are shown in Table 2.

[0019]

[0020]

As can be seen from Tables 1 and 2, the polyolefin composite fiber containing the alkyl sulfonate Na salt in the fiber surface-forming component in an amount within the range specified in the present invention has polypropylene as the surface. However, it is excellent in permanent hydrophilicity, has sufficient spinnability at the time of spinning, has no smoke, and does not pose a practical problem, and industrial production is possible. On the other hand, when the alkyl sulfonate Na salt is not contained, or even when it is contained in a content outside the range specified in the present invention, the hydrophilicity is insufficient, or even if it is sufficient, the spinnability is insufficient. It turns out that it is defective and cannot be put to practical use.

[0022]

INDUSTRIAL APPLICABILITY The hydrophilic polyolefin composite fiber according to the present invention has not only a portion where the fiber surface is formed of polyethylene but also a portion where the fiber surface is formed of polypropylene on the fiber itself and over the entire surface thereof. It has a permanent hydrophilicity and can be produced without the harmful effects of fuming during spinning. When such a hydrophilic polyolefin composite fiber according to the present invention is made into a non-woven fabric and used as a skin material such as a paper diaper, a characteristic skin material utilizing its crimpability and thermal adhesiveness is obtained, and in the manufacturing process thereof. It maintains good hydrophilicity even after the first urination after washing with water or wearing it, so that it always allows urine, etc. to pass quickly, does not cause rashes, etc., and does not emit smoke. Since it can be produced below, the production amount can be increased and used to further expand the application as a skin material for sanitary materials.

Claims (5)

[Claims] 1. A composite fiber comprising at least a fiber surface-forming component comprising two kinds of polyolefins, each of which has propylene and ethylene as main monomer components, and which independently constitutes each of two or more sections in the fiber cross section. To
A hydrophilic polyolefin composite fiber, characterized in that the alkyl sulfonate Na salt is contained in an amount of 0.5 to 5% by weight based on the total amount with the fiber surface forming component. 2. The alkyl sulfonate Na salt has an alkyl group R having 10 to 20 carbon atoms in the formula (I) R—SO ₃ Na ... (I). The hydrophilic polyolefin composite fiber according to. 3. The hydrophilic polyolefin composite fiber according to claim 1, wherein the composite fiber has a side-by-side composite structure, and any of the composite components contains an alkyl sulfonate Na salt. 4. The hydrophilic polyolefin composite fiber according to claim 1 or 2, wherein the composite fiber has a sheath-core type composite structure, and the sheath component contains an alkyl sulfonate Na salt only. 5. The hydrophilic polyolefin composite fiber according to claim 4, wherein the sheath component is a polyolefin containing ethylene as a main monomer component.