JPH0382816A - Binder fiber for nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent spinnability and heat- welding property and suitable for carpet, felt, etc., by melt-spinning a straight- chain low-density PE consisting of a copolymer of ethylene and an alpha-olefin and having specific density, melt-flow rate, etc. CONSTITUTION:The objective fiber can be produced by melt-spinning a straight- chain low-density PE consisting of a copolymer of ethylene and a 3-12C alpha-olefin and having a density of 0.85-0.91g/cm<3> (preferably 0.87-0.91g/cm<3>), a melt flow rate of 3-100g/10min (preferably 5-50g/10min) and an Mw/Mn ratio of <=4 (preferably <=3.7) (Mn is number-average molecular weight: Mw is weight-average molecular weight).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to binder fibers for nonwoven fabrics, and more specifically, the present invention relates to binder fibers for nonwoven fabrics, and more specifically, the heat fusion properties used in manufacturing nonwoven fabrics by bonding constituent fibers of nonwoven fabrics by heat fusion bonding. It relates to an excellent binder fiber, which is useful as a binder fiber for various nonwoven fabric products such as carpets, felts, waste materials, and liquid-absorbing materials.

[Conventional technology]

Conventionally, as a binder fiber material for this type of nonwoven fabric,
Branched low-density polyethylene, ethylene-vinyl acetate copolymer, and high-density polyethylene are used, but although the former two have excellent thermal bonding properties at low temperatures and in a short time, they do not melt easily. There are problems with poor spinning properties, such as difficulty in spinning at high speeds and drawing at high magnifications because the fibers are easily cut during spinning.On the other hand, although the latter has excellent spinning properties, There is a problem in that thermal fusion properties are poor, such as insufficient fusion strength being obtained by thermal fusion bonding.

[Problem to be solved by the invention]

The present invention has been made to solve the problems in the prior art described above, and therefore, the present invention provides binder fibers for nonwoven fabrics that have not only excellent spinning properties but also excellent thermal bonding properties. The purpose is to

[Means to solve the problem]

The binder fiber for nonwoven fabrics of the present invention is a copolymer of ethylene and α-olefin having 3 to 12 carbon atoms, and has a density of 0.85 to 0.91 f/m and a melt flow rate of 3 to 100 f/m. It is made by melt-spinning linear low density polyethylene having a ratio of weight average molecular weight to number average molecular weight of 4 or less for 10 minutes.

The linear low density polyethylene used in the present invention can be produced by a gas phase fluidized bed method, a solution method, or a pressure of 20 ok in the presence of an ionic polymerization catalyst such as a Ziegler type catalyst or a Kaminsky type catalyst.
By applying a polymerization process such as high-pressure ionic polymerization at a temperature of 150° C. or higher, ethylene and an α-olefin having 3 to 12 carbon atoms, preferably 4 to 8 carbon atoms, such as propylene, butene-1, pentene-1, etc. 1, hexene-1,4-methylpentene-1, heptene-1, octene-1, nonene-1, decene-1, etc., preferably butene-1, hexene-1,4-methylpentene-1, octene -1, etc., and is obtained by copolymerizing them.

This linear low density polyethylene in the present invention has a density of 0.85 to 0.91? /d.

Preferably 0.87 to 0.91 l/d, melt fluorate 3 to 100 S+/10 min, preferably 5 to soy/d
weight average molecular weight MW relative to number average molecular weight MN
The O ratio MW/MN is 4 or less, preferably 3.7 or less.

Here, it is difficult to commercially obtain a fiber having a density of less than 0.91 P/d, and a fiber having a density of less than 0.91 P/d has poor heat-fusibility as a binder fiber. Star,
If the melt flow rate is less than 3 f/10 minutes, the spinning properties will be poor, and if it exceeds 100 f/10 minutes, the strength of the fiber itself will decrease, resulting in a problem with the heat fusion properties as a binder fiber. Furthermore, if Mw/MN exceeds 4, gelation and oxidative deterioration are likely to occur during melt spinning, resulting in poor spinning properties and poor heat fusion properties as a binder fiber.

The binder fiber for nonwoven fabrics of the present invention includes the linear low-density polyethylene, an antioxidant, an ultraviolet absorber, a heat processing stabilizer, a colorant, a lubricant, which are usually added to polyolefin materials for fibers, as necessary. It is produced by adding additives such as antistatic agents, deodorants, antibacterial agents, matting agents, etc., and melt-spinning by a known method.

However, in producing a nonwoven fabric using the binder fiber for nonwoven fabric of the present invention as a binder fiber, for example,
One or more types of nonwoven fibers such as natural fibers such as cotton and wool, semi-synthetic fibers such as viscose rayon and cellulose acetate fibers, and synthetic resins such as polyolefin fibers, polyamide fibers, polyester fibers, and acrylic fibers. In contrast, the binder fiber A fiber of the present invention is usually added in an amount of 5% by weight or more,
After forming a nonwoven fabric by a known method used in general nonwoven fabric production, such as a carding method or an airlay method, it is then processed by a similarly known heat fusion treatment method, such as a dryer such as a hot air dryer, a suction drum dryer, or a Yankee dryer; Heat fusion treatment is performed using a calender roll, an embossing roll, or the like.

[Action and effect]

The binder fiber for nonwoven fabrics of the present invention is made by melt-spinning a specific linear low-density polyethylene, and has not only excellent spinning properties but also excellent heat-fusion properties.

〔Example〕

Examples 1 to 6, Comparative Examples 1 to 2 Copolymers of ethylene and α-olefin shown in the table, which have the density, melt flow rate, and MW/MN shown in the table.
Linear low-density polyethylene having the following properties was melt-spun at a spinning temperature of 200°C using a spinneret with a hole diameter of 1 m to obtain an undrawn yarn tow with a spun yarn fineness of 10 denier, and the undrawn yarn tow was then heated. After stretching and applying mechanical crimps at a number of 10 crimps/inch using a stuffer box crimper,
Stable binder fibers were produced by cutting the fibers into lengths of 51 m.

This binder fiber was mixed with a polypropylene table having a fineness of 20 denier and a fiber length of 51 in the proportions shown in the table, fed to a roller card to form a nonwoven fabric, and then pressed under no load and heated with a hot air through-type dryer to 105 denier. A nonwoven fabric (40y/rr?) was produced by heating at ℃ for 3 minutes and bonded by heat fusion with binder fibers, and the strength of the nonwoven fabric was measured.

Comparative Examples 3 to 5 Branched low-density polyethylene (Comparative Example 3), ethylene-vinyl acetate copolymer (Comparative Example 4), and high-density polyethylene (Comparative Example 5) having the density, melt flow rate, and Mw7MIN shown in the table were used. Binder fibers were produced in the same manner as in the examples, except that the fibers were used, and nonwoven fabrics were produced using these binder fibers.

(Left below) Button, where, density, melt flow rate, Mw/MN
, spinning characteristics, button strength, and nonwoven fabric strength were measured and evaluated by the following methods.

Density: JIS K6760 (density gradient tube method) Melt flow rate: JIS K6760MW/MN
: Ratio of weight average molecular weight Mw to number average molecular weight MN measured by Tegel permeation chromatography at 140°C in 0-di-chlorobenzene solution.

Spinning characteristics Spinability: Use a melt tension tester manufactured by Toyo Seiki Co., Ltd. with a diameter of 2
．． A 1 m nozzle is set and filled with sample 72.

After setting the temperature at 140 DEG C., the piston rod is lowered at a rate of 5 seconds per minute and the extruded molten strand is drawn off through counter-rotating rolls with a radius of 70 mm.

At this time, the rotational speed of the roll is gradually increased, and the take-up speed at which the strand is cut is taken as a measure of spinnability.

Stretchability: ○ indicates that single fiber breakage does not occur even at a draw ratio of 4.0 times or more during the drawing process after melt spinning, and ○ indicates that the draw ratio is 4.
A case where single filament breakage occurs at 0 times or more is evaluated as × and is used as a guideline for stretchability.

Nonwoven Fabric Strength Measurement was carried out in accordance with JIS L1085 (Nonwoven Fabric Tensile Test Force Method) using a test piece with a width of 5 cyt at a gripping interval of 10 crn and a tensile speed of 30±2 cm.

Claims (1)

[Claims] A copolymer of ethylene and α-olefin having 3 to 12 carbon atoms, with a density of 0.85 to 0.91 g/cm^3
, a binder fiber for a nonwoven fabric obtained by melt-spinning linear low-density polyethylene having a melt flow rate of 3 to 100 g/10 minutes and a ratio of weight average molecular weight to number average molecular weight of 4 or less.