JPH05179511A - Thermally adhesive conjugate fiber, fiber assembly therefrom and fiber assembly provided with electret nature - Google Patents

Abstract

PURPOSE:To provide the subject conjugate fiber usable as thermally adhesive fiber with the sheath component consisting of polybutene-1, produced by efficient melt spinning, and to obtain an air filter by electrifying a fabric made from the fibers. CONSTITUTION:The objective conjugate fiber made up of (A) as sheath component, polybutene-1<3 in Q-value, 0.5-15 in melt index, 0.905-0.930 in density and 115-130 deg.C in melting point and (B) as core component, another polymer 150-300 deg.C in melting point. The conjugate fibers are drawn by a factor of >=1.5 in hot water and made into a nonwoven fabric, which is, in turn, electrified in an atmosphere not lower than the melting point of polybutene-1, thus affording an air filter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention can withstand use at higher temperatures than conventional non-woven fabrics using heat-adhesive fibers containing polyethylene as an adhesive component, so that it is difficult to apply heat-adhesive fibers to air-conditioning air filters. In addition, since the electrification property is better than that of polyethylene, the electret fiber aggregate becomes a superior electret fiber aggregate when heat-bonded during heat-adhesion processing, and a heat-adhesive conjugate fiber and its fiber aggregate suitable as an air filter or wiper. Regarding

[0002]

2. Description of the Related Art Polybutene-1 has a melting point of 130 ° C. or less, but is difficult to be made into a fiber, and is known only as a core component of a core-sheath type composite fiber in JP-A-56-15417.

[0003]

Since polybutene-1 has a three-dimensional structure different from that of other polyolefins, it undergoes a peculiar crystal modification, has a slow crystallization rate, and is melt-spun and bundled even if cooled in cold air in a draft. It was difficult to form single fibers due to fusion between the fibers. Further, since it has a long side chain, the drawability is poor, and it was not possible to obtain a high strength by performing a drawing operation.
However, polybutene-1 is less likely to deteriorate even at temperatures over 100 ° C, and can be used continuously, and since it has superior charging characteristics to polyethylene, it is convenient for air conditioning air filters if it is electret processed into a fiber aggregate such as nonwoven fabric. Can be expected to be available. Therefore, it has been desired to efficiently produce and utilize polybutene-1 like other α-polyolefins such as polypropylene.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have found that polybutene-1 (PB-1) has an appropriate ballasting effect and a strong temperature dependence when a polymer having a Q value of less than 3 and having a narrow molecular weight distribution is selected. As a result of earnest studies, knowing that it exhibits stretchability, the present invention has been achieved.

The PB-1 used in the present invention has a melt index (MI: g / 10) in order to prevent fusion between fibers.
Min) is 0.5 <MI <15, 15 or more, especially 20
If it is above the range, fusion tends to occur, which is not preferable, and if it is below 0.5, the composite spinning is difficult.

Further, it is preferable to use fine clay powder or the like as a nucleating agent to promote crystallization.

That is, in the present invention, the Q value (weight average molecular weight /
Ratio of number average molecular weight) is less than 3, melt index (M
I: g / 10 minutes, measurement temperature 190 ° C., weighted 2.169 k
g, not according to JIS-K-6760. ) 0.5 <MI <
15. Density (Dg / cm ³ ) 0.905 ≦ D <0.9
30, polybutene-1 having a melting point (Tm ° C.) of 115 <Tm <130 as a sheath component, and a melting point (Tm ° C.) of 150 ≦
A core-sheath type thermo-adhesive conjugate fiber comprising a fiber-forming thermoplastic polymer having Tm ≦ 300 as a core component.

The fiber-forming thermoplastic resin, which is the core component of the composite fiber, has a melting point (Tm ° C.) higher than the melting point of PB-1 by 20 ° C. or more, that is, at 150 ° C. or higher, for the sake of utilizing it as a thermoadhesive fiber. Preferably, the temperature is lower than 300 ° C. for the sake of melt-composite spinning, and specifically, polyolefin such as polypropylene and polymethylpentene, polyester such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 66, nylon 6
-10, MXD6 nylon (trade name, manufactured by Mitsubishi Gas Chemical Co., Inc.), polyamide homopolymers such as nylon 12, copolymers and graft modified products are convenient.

In many applications, such as air-conditioning air filters or hot water filters, which need to withstand high temperatures, not only heat resistance but also strength is required. It is preferable to improve the strength of the. Therefore, the conjugate fiber of the present invention is preferably in the form of staple fiber, staple fiber for papermaking, multifilament or monofilament which has been stretched at least 1.5 times or more, and adversely affects the charging property in a field requiring a charging function such as an electret filter. Fiberizing is preferably carried out by spunbonding or meltblowing techniques which do not require the use of fiber treatment agents. When staple fibers are used, the fiber treatment agent may be in the form of spunlace nonwoven fabric capable of being washed and removed.

The fiber of the present invention is most preferably a core-sheath type composite fiber having PB-1 as a sheath component, but the core component is eccentric and the core component occupies 40% or less of the fiber surface on the fiber surface. It may be exposed, or may be a multi-core type having a plurality of core components. The area composite ratio of the core component and the sheath component in the fiber cross section is preferably 70:30 to 20:80. Further, the fiber cross section may be a polygonal shape having a circular or rounded outer shape, or a T-shaped or dodecagonal modified cross-section, or may be a hollow type having a hollow fiber center portion, and the fineness thereof is 0.5 to
It is 100 denier.

The fiber aggregate referred to in the present invention means a non-woven fabric,
It means paper, felt, cotton, woven or knitted fabric, spun yarn, flocked product, etc. If the composite fiber of the present invention is contained in an amount of 30% by weight or more, it is effective as a heat-adhesive fiber, and when used as a charged fiber. Is preferably contained in an amount of 50% by weight or more.

That is, at least 30% by weight of the core-sheath type thermoadhesive conjugate fiber of the present invention is mixed with another fiber having a melting point higher than that of polybutene-1, which is a sheath component of the fiber, to obtain at least a sheath component. Is a fiber assembly characterized by being melt-bonded and integrated with polybutene-1.

As the fiber aggregate to be electret, 100 to 50% by weight of the core-sheath type composite fiber of the present invention and a polyolefin fiber 0 having a polyolefin fiber surface are used.
Polybutene-1 containing 50% by weight of at least sheath component
The fiber assembly is characterized in that it is melt-bonded and integrated with each other, and at least polybutene-1 is charged.

When the fiber of the present invention is used as a charged fiber (electret fiber), it is most preferable that the fiber is formed by a spunbond or meltblown method capable of forming a fiber aggregate without using a fiber treatment agent in order to prolong the charging life. Alternatively, staples using an easily water-soluble fiber treating agent may be formed into a fiber aggregate by a spunlace method to remove the fiber treating agent, and then the direct current is increased at a temperature 10 ° C lower than the melting point Tm of PB-1 or higher. It is convenient to place it under a voltage, charge it to a negative charge, and rapidly cool it so that it becomes an electret.

In this case, not only the fiber of the present invention which is electretized, but also other fibers to be mixed must not be attached with an antistatic agent such as a surfactant which hinders electretization.

When used as a mixed cotton or a mixed layer with other fibers, the other fibers are electrically insulating fibers, for example, heat-adhesive composite fibers containing polyolefin such as polyethylene as a sheath component.
Conveniently is a polyolefin-based fiber having a polyolefin surface such as polypropylene or polymethylpentene, which may be a single component fiber or a bicomponent fiber.

The electretized fiber assembly of the present invention comprises
It is also preferred that the fiber assembly comprising heat-bondable fibers having a function as a reinforcing or pre-filter or a microfiltration filter is heat-bonded, which is before the fibers of the present invention are electretized or at the same time as the electretization step. Can be heat-bonded.

[0019]

The PB-1 used in the fiber of the present invention has a small Q value of less than 3, so that it has an appropriate ballast effect during melt spinning, is easy to spin, and has stretchability. When used as an adhesive fiber, since the core component can be drawn together with PB-1, it can be made into a fiber having a higher strength and a lower elongation than the undrawn fiber, and a fiber having a fineness can be obtained.

Since the fiber of the present invention contains PB-1 as a heat-bonding component, the heat-bonding processing temperature is 135 to 150 ° C., which is exactly the same as that of a polyethylene-based heat-bonding fiber having polyethylene as a heat-bonding component. Nevertheless, it can be used as a heat resistant filter or a heat resistant water filter at a temperature of about 100 ° C., which is about 30 ° C. higher than that of conventional polyethylene-based heat-bonded fibers.

Since PB-1 has a longer side chain than polyethylene and polypropylene, it is easily polarized and has a melting point of 115 to 130 ° C., which is a temperature at which a general-purpose heat processing machine can be used, and is not a high melting point like polymethylpentene. Therefore, it is most suitable as a general-purpose electret material, and since it uses a core component with a high melting point, the fiber form can be maintained even if it is heat-bonded. An excellent electret nonwoven fabric can be obtained.

[0022]

【Example】

[Examples 1 to 5, Comparative Examples 1 to 3] With the combinations shown in Table 1, concentric core-sheath composite fibers were melt-spun at a composite ratio of 50:50 to obtain undrawn yarns. At this time, the presence / absence of the fused yarn was also evaluated, and it was determined to be none (⊚), to some extent not practically available (∘), and present (x). The undrawn yarn was drawn in boiling water at 95 to 98 ° C. or hot water at 80 ° C., and the maximum draw ratio at which single fiber breakage did not occur at this time was measured.

After the easily water-soluble fiber treating agent was added to the drawn yarn and mechanical crimping was performed in a stuffing box, 1
Dry using a conveyor type hot air dryer at 00 ° C,
The staple fiber was cut into 51 mm. This staple fiber is opened using a roller card, and 60 g / m
² basis weight of the web and without, and 140 ° C. hot air through heat processing machine for 2 minutes processed and thermal bonding nonwoven fabric, using a nonwoven fabric sample of 5cm width, measured breaking strength and elongation of the nonwoven fabric at room temperature and 80 ° C. in an atmosphere The results are shown in Table 1.

[Example 6] The fibers of Example 1 and 2 denier polypropylene staple were mixed in an amount of 50% by weight to form a nonwoven fabric in the same manner as in Example 1, and the breaking elongation at 80 ° C was measured. It was 70% at 2.5 kg.

Example 7 Using the fiber of Example 1, 6
Without a web with a weight of 0 g / m ² , spun laced with pressure water of 50 kg / cm ² and immersed in fresh fresh water at 60 ° C-
After centrifugal dehydration was repeated 20 times, it was dried in a 100 ° C. dryer to obtain a degreased nonwoven fabric in which the fiber treatment agent previously attached was completely removed. When this nonwoven fabric was subjected to negative application of 45 kv in an atmosphere of 140 ° C. for 1 hour and then cooled to room temperature as it was, static electricity of 10 kv was obtained, and a value of 4 kv was shown even after 1 week.

[0025]

[Table 1]

[0026]

EFFECTS OF THE INVENTION The composite fiber of the present invention, when used as a non-woven fabric for a filter or a heat-bonding fiber for a mold type cartridge filter, can be sufficiently heat-bonded even at 150 ° C. or lower. The heating air that can be used and has a continuous usable temperature of around 100 ° C, which is about 30 ° C higher than that using conventional heat-bonding fibers, cannot use conventional general-purpose heat-bonding fibers, and uses resin processed products. It is possible to supply filters with high lint-free properties in the fields of filters and cartridge filters for hot water.

The electret non-woven fabric made of the fiber of the present invention containing no fiber treating agent can be replaced with the electret non-woven fabric of polypropylene fiber which has been conventionally used. By combining it with other fiber materials, the performance is further improved. It is convenient to supply the filter.

Claims (3)

[Claims] 1. A Q value (ratio of weight average molecular weight / number average molecular weight) of less than 3, and melt index (MI: g / 10).
Min, measurement temperature 190 ℃, weight 2.169kg, JIS-K
According to -6760. ) 0.5 <MI <15, density (D
g / cm ³ ) 0.905 ≦ D <0.930, melting point (T
(mC) 115 <Tm <130 is used as a sheath component, and a fiber moldable thermoplastic polymer having a melting point (Tm ° C) of 150≤Tm≤300 is used as a core component. Heat-bondable composite fiber. 2. At least 30% by weight of the core-sheath type heat-bondable composite fiber according to claim 1 is mixed with another fiber having a melting point higher than that of polybutene-1 which is a sheath component of the fiber, A fiber assembly characterized by being melt-bonded at least with polybutene-1 as a sheath component and integrated. 3. A core-sheath type composite fiber 100 according to claim 1.
50% by weight and 0 to 50% by weight of a polyolefin fiber having a polyolefin fiber surface, and melt-bonded at least with polybutene-1 as a sheath component to be integrated,
A fiber assembly characterized in that at least polybutene-1 is charged.