JPH02221448A - Moisture-retentive nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain the title product which is suitable for wiping cloth, because of excellent water retention and durability in addition to its intrinsically excellent mechanical properties by using polyolefin conjugated fibers containing a specific surface active agent in one polyolefin component. CONSTITUTION:The subject product is a nonwoven fabric in which polyolefin conjugated fibers are heat-treated to fuse the crossing points of the fibers and the first polyethylene component contains 3 to 10wt.% of a monoglyceride of 12C or more fatty acid such as lauric acid monoglyceride. The polyolefin conjugated fibers comprises the first component of polyethylene and the second component of crystalline polypropylene or thermoplastic polyester so that the first component constitutes at least a part of fiber surface along the longitudinal direction of the fibers.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a nonwoven fabric using polyolefin composite fibers, and more specifically to a nonwoven fabric in which contact points of fibers obtained by heat-treating the composite fibers are fused. The present invention relates to a nonwoven fabric that has excellent hydrophilicity and water retention properties and can be used in fields such as battery separators and wiping cloths.

(Prior Art) Nonwoven fabrics are known in which polyolefin composite fibers such as polypropylene/polyethylene and polyester/polyethylene are heat-treated and the contact points of the fibers are fixed by fusion of the low melting point components.

Although such nonwoven fabrics have excellent mechanical properties and chemical resistance, they are inherently hydrophobic, making them unsuitable for applications that require hydrophilicity, such as battery separators and wiping cloths. .

In order to impart hydrophilicity to polyolefin nonwoven fabrics, there is a method of coating raw material fibers or nonwoven fabrics with a surfactant, but the surfactant washes away during use, making it difficult to maintain stable hydrophilicity for a long period of time. It is. In addition, methods to impart hydrophilic properties by mixing polyvinyl alcohol with polyolefin or combining polyamide (Graph 11) are also known, but these methods are not practical due to insufficient fiber properties or being uneconomical. has not been standardized.

[Problem to be solved by the invention]

The present invention has been developed without impairing the mechanical properties and chemical resistance, which are the original characteristics of nonwoven fabrics made of polyolefin composite fibers.
The purpose is to provide durable water retention easily and inexpensively.

(Means for Solving the Problems) In order to solve the above problems, the present inventor has conducted intensive research and found that the desired purpose can be achieved by incorporating a specific surfactant into the first component of the composite fiber. Furthermore, it was discovered that by kneading polyvinyl alcohol or polyamide into the first component, the liquid-retaining property could be further improved, thereby maintaining excellent water-retaining property for a long period of time. Then, the second invention and the third invention of the present application were completed.

The polyolefin composite fiber used in the present invention is composed of crystalline polypropylene or thermoplastic polyester (hereinafter both may be collectively referred to as the second component) and polyethylene (hereinafter sometimes referred to as the first component). 1
It is a fiber that is composite-spun in a sheath-core type or parallel type so that the components form at least a part of the fiber surface along the length of the fiber. The composite ratio of both components is 70/30~30
/70 (volume ratio) is preferable. The first component is 30
If it is less than 770, the adhesive strength between the fibers of the nonwoven fabric obtained by heat-treating it will be insufficient, and if the first component is less than 770/
If it exceeds 30, the strength of the fibers themselves will be insufficient, and therefore the strength of the nonwoven fabric will decrease in either case, which is not preferable.

The specific surfactant used in the present invention is a monoglyceride of a fatty acid having 12 or more carbon atoms, specifically Vi
Examples include lauric acid monoglyceride, stearic acid monoglyceride, and oleic acid monoglyceride. These surfactants may be used alone or in combination of two or more. The amount of surfactant mixed into the first component of the composite fiber is 3 to 10% (X amount) based on the first component. If the amount of kneading is less than 3%, the degree of improvement in water retention of the obtained nonwoven fabric is low;
If it exceeds this, the spinnability of the composite fiber will decrease, which is not preferable.

The polyvinyl alcohol used in the present invention is mel) 7
(according to condition 4 of JIS K 7210. Table 1) is 10g/10ml or more, degree of saponification 30-70
An example is %.

In addition, polyamides include nylon 6, nylon 6.6
Examples include polyamides for ordinary fibers such as nylon TE1. The amount of kneading in the polyvinyl alcohol or polyamide 0 first component is 15% (! amount) or less. If the amount of kneading exceeds 15%, phase separation with the first component may occur, resulting in a decrease in spinnability and a decrease in the strength of the melting point of the first component in the nonwoven fabric. Examples include zeolite, silica gel, etc., which have an average particle size of 5 microns or less and a particle size of 10 microns or more in a content of 5% or less, and these porous fine particles are impregnated with the surfactant and used. The amount of the fine powder contained in the second component is 10% ('x amount) or less, and if it exceeds 10%, the spinnability deteriorates, which is not preferable.

〔Example〕

The present invention will be explained in more detail with reference to Examples and Comparative Examples. The definitions of terms used on each side and the methods for measuring physical properties are as follows.

Spinnability: Items in which single yarn breakage occurs more than once per minute are marked as unacceptable, and items in which single yarn breakage occurs less than once per minute and 2 or more times in 10 minutes are acceptable. It is indicated as Δ, and those in which single thread breakage occurs less than once in 10 minutes are considered good and indicated as 0.

Fiber strength: According to the tensile strength measurement method of JIS L 1013 (chemical fiber filament yarn testing method), the breaking strength measured at a grip interval of 200 g and a tensile speed of 20 cII/min is 2 da/d or more, and 0 is considered good. Items less than 2 da/d are not allowed and are marked with an x.

Water retention: A sample piece (10mxlOa*) cut from the sample nonwoven fabric (fabric weight 601/nf) was treated with 0.2% dioctyl sulfosuccinate and 0 hyisopropyl alcohol.
．． After 10 minutes of immersion in 30 ml of wash water containing 1%, vertical KM! Repeat the operation t-10 times to turn off the liquid. After that, 500 ml of ion-exchanged water was added in a suspended state.
111 and air dry at room temperature for 24 hours. Weight (D
) t-measured air-dried sample ft After being immersed in a 30% KOH aqueous solution at room temperature for 60 minutes, the sample was hung vertically for 10 minutes, the liquid was drained, and the weight (W) was measured. Water retention rate 1oox CW-
D)/DIC.

Durable water retention: After washing a nonwoven fabric sample piece (10nx 10c11) in the same manner as in the water retention test, it was washed with ion-exchanged water 6
Store at room temperature in 0 g/ml for 1 year. After air-drying this preserved sample piece, it is immersed in a 30% KOH aqueous solution to measure the water retention rate.

Examples 1 to 6, Comparative Examples 1 to 7 The first extruder was equipped with a melt flow rate (9710 m1n
, 190°C) 25 high-density polyethylene, a surfactant, polyamide or polyvinyl alcohol of the type and amount shown in Table 1, and melt flow rate) (f/10m1n, 230℃)3
The crystalline polypropylene of No. 5 was supplied, and the extrusion rate and extrusion temperature of both extruders were both 600 f/hr and the extrusion temperature was 250 ° C. Composite spinning was performed using a parallel composite spinneret (number of holes: 100) for 15 d. An undrawn yarn of /f was obtained, which was drawn three times, mechanically crimped (12 threads/25m+1), and then cut to a length of 51ffK to obtain a stable yarn of 5d/f. This staple is made into a web using a roller card machine.
Heat treatment was performed at 140° C. for 3 minutes using a suction dryer to obtain a nonwoven fabric (fabric weight: 601/yyf) in which fiber contacts were fixed by fusion of high-density polyethylene.

Test pieces (10 cI 11 x 101) were cut out from these nonwoven fabrics and their physical properties were measured. The results are also shown in Table 1.

Examples 7 and 8, Comparative Example 8.9 High-density polyethylene and stearic acid monoglyceride (3%) were supplied to the first extruder in the same manner as in Example 1, and the second extruder was supplied with the same amount as in Example 1. A nonwoven fabric was obtained in the same manner as in Example 1 except that the crystalline polypropylene used and the surfactant-containing zeolite shown in Table 2 were supplied. The physical properties of these nonwoven fabrics are shown in Table 2.

〔effect〕

As is clear from the data shown in Tables 1 and 2, the nonwoven fabric of the present invention made of composite fibers containing a specific surfactant retains water even after being washed 10 times with washing water. Stones that are large in size and contain porous particles impregnated with surfactants can maintain excellent water retention for a long period of time. Such nonwoven fabrics with excellent water retention properties are suitably used as battery separators and wiping cloths. On the other hand, when the surfactant is not contained or when it is attached to the fiber surface as a spinning oil, the water retention property is poor.

Sekigi July 21, 1999 1999 Patent Application No. 40, O 73 3-6-32 Nakanoshima, Kita-ku, Osaka, Osaka Prefecture (530)
(207) Chisso Co., Ltd. Representative Sadao Nogi 4, Agent 2-8-1 Shinjuku, Shinjuku-ku, Tokyo (160) (Telephone 354-1285) - Bon.

Claims (3)

[Claims] (1) A nonwoven fabric in which fiber contacts obtained by heat-treating polyolefin composite fibers are fused, and the first component of the composite fiber contains 3 to 10% (by weight) of fatty acid monoglyceride having 12 or more carbon atoms. A water-retaining nonwoven fabric characterized by (2) The water-retaining nonwoven fabric according to claim (1), characterized in that the first component of the composite fiber further contains 15% (weight) or less of polyvinyl alcohol or polyamide. (3) The water-retaining nonwoven fabric according to claim (1) or (2), wherein the second component of the composite fiber is impregnated with 10 or more porous characteristic particles impregnated with a monoglyceride of a fatty acid having 12 or more carbon atoms.
% (weight) or less of water-retentive nonwoven fabric.