JPH01246413A - Production of polyolefinic yarn - Google Patents

Abstract

PURPOSE:To economically obtain the title yarn providing nonwoven fabric having binder function by a simple device, by subjecting a resin composition consisting of a specific propylene (co)polymer and a specific butene-1 (co)polymer to melt spinning under a specific condition. CONSTITUTION:A resin composition consisting of (A) 30-90wt.% propylene, homopolymer having 4-80g/10 minutes melt index (MI) and <=6 ratio of weight- average molecular weight Mw/number-average molecular weight Mn and/or propylene-ethylene copolymer containing <=25wt.% ethylene unit and (B) 70-10wt.% butene-1 homopolymer having 1-80g/10 minutes MI and <=6 ratio of Mw/Mn and/or butene-1 copolymer having <=35wt.% another alpha-olefin unit content is subjected to melt spinning at 180-300 deg.C die temperature and 500-5,000 draw ratio to give the aimed yarn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing polyolefin fibers having excellent thermal adhesive properties. More specifically, the present invention relates to an economically advantageous method for producing ultrafine polyolefin fibers having thermal adhesive properties suitable for producing nonwoven fabrics having a binder function at relatively low temperatures using a die with a simple structure. It is something.

[Prior Art] In recent years, composite fibers with thermal adhesive properties have been developed in place of chemical binders, and these composite fibers not only have good thermal adhesive properties at fiber-to-fiber contact areas, but also have excellent adhesive properties for dissimilar materials such as cloth, wood, and metal. For example, it can be cut into stable fibers of an appropriate fiber length to form a web, and heated to simultaneously form a non-woven fabric and bond it to a different material. Demand for it is increasing as a material for disposable diapers and sanitary products, as well as for medical use and paper making.

Composite fibers with such thermal adhesive properties have conventionally been made by arranging components consisting of two types of resins with different melting points in parallel or in a sheath-core shape in the length direction of the fibers to impart thermal adhesive properties. For example, a first component consisting of crystalline polypropylene and a second component consisting of an ethylene-vinyl acetate copolymer or a saponified product thereof having a lower melting point are arranged in a parallel type or sheath-core type composite. , in which the second component is formed continuously in the length direction on at least a portion of the fiber surface (Japanese Patent Publication No. 54-4473, Japanese Patent Publication No. 54-4474)
Alternatively, a polymer containing polypropylene as the first component and polybutene as the second component is used, and these are composited in parallel to the fiber axis (Japanese Patent Laid-Open No. 49-10
No. 1669) and the like are disclosed. However, such composite fibers with thermal adhesive properties require dies with complicated shapes to manufacture, and also require processing from short fibers when manufacturing nonwoven fabrics.
It has drawbacks such as the number of steps involved.

Furthermore, a method has been proposed in which polybutene is used as the first component and a polyolefin other than polybutene or a mixture of polybutene and other polyolefins is used as the second component, and these are spun into a back and forth structure using a die equipped with a composite spinneret. However, this method also has the disadvantage that the equipment is complicated and the cost is inevitably high.

[Problems to be Solved by the Invention] Under these circumstances, the present invention has been developed by using heat-adhesive fibers that can easily produce a nonwoven fabric having a binder function using conventional nonwoven fabric equipment. The purpose of this invention is to provide an economically advantageous manufacturing method using a die having a unique structure.

[Means for Solving the Problem] As a result of extensive research to achieve the above object, the present inventors found that polypropylene and polybutene-1 have different melting points and good compatibility. Focusing on this, a resin composition containing a specific propylene homopolymer and/or propylene-ethylene copolymer and a specific butene-1 homopolymer and/or butene-1 copolymer in a predetermined ratio is , it is possible to spin fibers with a coagulated composite structure due to phase separation of each component at a lower temperature than conventional methods, without using a die with a complicated nozzle structure. We have discovered that a nonwoven fabric having a binder function can be easily obtained using the equipment used, and that the resin composition can be spun into ultrafine fibers of 10 deniers or less, and based on this knowledge, we have completed the present invention. Ta.

That is, in the present invention, (A) the melt index is 4 to
Propylene homopolymer and/or propylene-ethylene copolymer having 25% by weight or less of ethylene units 30 to 90 with a weight average molecular weight (Mw)/number average molecular weight (Mn) ratio of 809/10 minutes and 6 or less (B) a butene-1 homopolymer having a melt index of 1 to 809/10 minutes and a weight average molecular weight (Mw)/number average molecular weight (Mn) ratio of 6 or less and/or other A resin composition consisting of 70 to 10% by weight of a butene-1 copolymer having a unit content of σ-olefin of 35% by weight or less was prepared under conditions of a die temperature of 180 to 300°C and a draw ratio of 500 to 5ooo. The present invention provides a method for producing polyolefin fibers characterized by melt spinning.

The present invention will be explained in detail below.

In the resin composition in the method of the present invention, a propylene homopolymer and/or a copolymer of propylene and ethylene is used as component (A).

In the copolymer, the content of ethylene units must be 25% by weight or less, preferably 20% by weight or less. If the content of this ethylene unit exceeds 25% by weight, the spun yarns tend to stick to each other. There are no particular restrictions on the method for producing these propylene homopolymers and copolymers, and conventionally known polymerization methods can be used. In addition, the obtained propylene homopolymer or copolymer may be used as it is, or may be degraded with peroxide or the like. These reduced products may be used in appropriate combination.

In the present invention, the propylene homopolymer or propylene-ethylene copolymer as the component (A) has a melt index CMI] of 44 to 809/110 minutes, preferably 6 to 609/10 minutes, and a weight average It is necessary that the ratio of molecular weight [Mwl/number average molecular weight [Mnl] be 6 or less, preferably in the range of 2 to 5.5. The M
If I is less than 49/10 minutes, spinnability will be poor and ultrafine fibers may not be able to be spun, and if I exceeds 80 g/10 minutes, eye stains and the like will tend to occur. On the other hand, M
When the w/Mn ratio exceeds 6, the fibers tend to break during stretching.

In the resin composition of the present invention, a butene-1 homopolymer and/or a copolymer of butene-1 and another σ-olefin is used as the component (B).

Other σ-olefins for which the butene-1 copolymer can be used include those having 2 to 8 carbon atoms, such as ethylene, furopylene, 4-methylpentene-1, hexene-1, octene-1, etc. Of these, ethylene and propylene are preferred. These α-olefins may be copolymerized with butene-1 alone, or
Two or more types may be combined and copolymerized. The content of other α-olefin units in the copolymer needs to be 35% by weight or less, preferably 25% by weight or less. If this content exceeds 35% by weight, the spun yarns tend to stick to each other. There are no particular restrictions on the method for producing these butene-1 homopolymers and copolymers, and conventionally known polymerization methods can be used. The obtained butene-1 homopolymer or copolymer may be used as it is, or may be degraded with peroxide or the like. - Other α-olefin copolymers and reduced products thereof may be used in appropriate combinations.

In the present invention, the butene-1 homopolymer or butene-1 copolymer as the component (B) has a melt index [M
I] is 00.5 to 809110 minutes, preferably 1.5
~609/10 minutes, and the weight average molecular weight [
It is necessary that the ratio of Mwl/number average molecular weight [Mnl] be 6 or less, preferably in the range of 2 to 5.5. The Ml
If it is less than 0.59/10 minutes, the spinnability is poor;
If it exceeds 10 minutes, there is a tendency for burns or eye discharge to occur. On the other hand, when the Mw/Mn ratio exceeds 6, the fibers tend to break during stretching.

The resin composition used in the present invention desirably has a low melting point in order to impart a binder function to the resulting fibers, and the faster the crystallization, the better in order to improve moldability. Therefore, as component (A), propylene-ethylene copolymer is preferable to propylene homopolymer,
On the other hand, as component (B), butene-1-ethylene random copolymer or butene-1-ethylene random copolymer is more suitable than butene-1 homopolymer.
A propylene random copolymer is preferred.

Regarding the blending ratio of component (A) and component (B) in the composition, component (A) is 30 to 90% by weight, preferably 45 to 85% by weight, and component (B) is 70 to 10% by weight. It is blended in a proportion of 55 to 15% by weight, preferably 55 to 15% by weight. If the amount of component (A) is less than 30% by weight, the yarns will stick to each other during spinning, making it difficult to obtain the desired fibers, and if it exceeds 90% by weight, it will be difficult for the fibers to adhere to each other during thermal bonding. It is necessary to increase the bonding temperature.

The resin composition used in the present invention includes various additives commonly used in polyolefin resin compositions, such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, flame retardants, antistatic agents, and colorants. etc. can be added as desired.

The resin composition is prepared by mixing required amounts of component (A), component (B), and various additives used as desired in various mixers,
It can be prepared by a known method of triblending using a kneader, an extruder, or the like.

The resin composition thus prepared has a die temperature of 1
Melt spinning is carried out under conditions of 80 to 300°C, preferably 180 to 220°C, and a draw ratio of 500 to 5,000, preferably 1,000 to 4,000.

If the die temperature is less than 180°C, the viscosity of component (A) will be high and the spinnability will be poor, and if it exceeds 300°C, the resulting fibers will be prone to stains or stains. It is generally said that the spinning temperature for polypropylene is 250°C or higher, but in the present invention, by blending a low melting point butene-1 homopolymer or copolymer with the propylene homopolymer or copolymer, The spinning temperature can be lowered to 180 to 220°C, and such a low spinning temperature is advantageous in preventing thermal deterioration of the resin and troubles during spinning (eye stain, stickiness of yarn, etc.). In addition, the temperature during cooling stretching is preferably lower to avoid stickiness of the yarn, and is usually 3.
The temperature is preferably 0°C or lower, preferably 20°C or lower.

If the draw ratio is less than 500, the resulting fibers will be thick and lack flexibility, while if it exceeds 5,000, the fibers will tend to break easily during drawing, resulting in poor spinnability. By spinning in this manner, ultrafine fibers of, for example, 20 deniers or less can be obtained. Further, in the spinning, there is no need to use a die having a cap with a complicated structure, and a die having a single-hole cap can be used.

The fibers obtained in this way form a cohesive composite structure of a butene-1 homopolymer or copolymer with a low melting point and a propylene homopolymer or copolymer with a high melting point. Because the butene-1 polymer and copolymer phase are easy to melt,
It has excellent thermal adhesive properties. Further, the fibers can be easily produced into a nonwoven fabric using equipment conventionally used for producing nonwoven fabrics. As a method for producing this nonwoven fabric, the spunbond method, which is an hourly process, is suitable in terms of moldability.

The polyolefin fiber obtained by the method of the present invention not only has good thermal adhesion in the fiber-to-fiber contact area, but also
It has thermal adhesion properties to different materials such as metals, and can be cut into stable fibers of an appropriate fiber length to form a web, and heated to simultaneously perform non-wovenization and adhesion to different materials. It is suitably used as a material for disposable diapers and sanitary products, as well as for medical purposes and paper making.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

The thermal adhesion test was conducted at a linear pressure of 40 kg/cm.
Thermal adhesion was evaluated according to the following criteria.

O: Good thermal adhesion.

Δ: It is thermally bonded but peeled off.

×: No thermal bonding.

Examples 1 to 12, Comparative Examples 1 to 9 Propylene polymer [A] having the composition shown in Table 1 and butene-
1 polymer [B] in the proportions shown in Table 1, 40
Using a mm-extruder, melt blending was performed at 220°C, and spinning was performed to produce a polyolefin fiber, and its thermal adhesion was determined.

A die with a normal single-hole spinneret was used for spinning.

The results are shown in Table 1.

(The following is a blank space) [Effects of the Invention] According to the method of the present invention, by using a resin composition containing a specific propylene polymer and a butene-1 polymer in a predetermined ratio, an ultrafine polyolefin with excellent thermal adhesive properties can be produced. The fibers can be produced economically and advantageously at relatively low temperatures using dies of simple construction.

The polyolefin fiber obtained by the method of the present invention can be easily provided as a nonwoven fabric with a binder function using equipment conventionally used for manufacturing nonwoven fabrics, and can be used as a material for disposable diapers, sanitary products, etc., or for medical treatment. It is suitable for use in industrial applications and paper making.

Patent applicant: Idemitsu Petrochemical Co., Ltd.

Claims (1)

[Claims] 1 (A) Melt index is 4 to 80 g/10 minutes, and weight average molecular weight (Mw) / number average molecular weight (Mn)
(B) a propylene homopolymer having a ratio of 6 or less and/or a propylene-ethylene copolymer having 25% by weight or less of ethylene units, 30 to 90% by weight, and (B) a melt index of 1 to 80 g/10 min, and Average molecular weight (Mw)/
A butene-1 homopolymer having a number average molecular weight (Mn) ratio of 6 or less and/or a butene-1 copolymer having a unit content of other α-olefins of 35% by weight or less and 70 to 10% by weight. A resin composition consisting of
A method for producing polyolefin fibers, which comprises melt spinning at 0°C and a draw ratio of 500 to 5000.