JPH01132861A - Heat-weldable nonwoven fabric - Google Patents

Abstract

PURPOSE: To produce hot-melting type nonwoven fabric comprising specific conjugated hot-melting type fiber groups having mutually different number of crimps in a specific content ratio, having high strength, bulkiness and soft feeling, and suitable for a covering paper for a diaper, Sanitary goods or the like. CONSTITUTION: The objective nonwoven fabric is a fiber cluster made of conjugated fibers each consisting of a polyolefin as the first component and a polyester as the second component. At least part of the first component exists in the surface of each fiber in an exposed and longitudinally continuous state and therefore the fiber is made to become conjugated hot-melting type fiber in the fiber cluster. The fiber cluster includes conjugated hot-melting type fiber groups respectively having (A) <=20/(25 mm) number of crimps and (B)>=40/(25 mm) number of crimps in weight contents of >=20 wt.% respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a heat-adhesive nonwoven fabric that has high strength, bulk, and soft texture.

(Prior Art) In recent years, as the uses of nonwoven fabrics have diversified, the performance required of nonwoven fabrics has also become more sophisticated and complex.

In particular, nonwoven fabrics used as covering materials for disposable diapers, sanitary products, etc. are required to have strong strength, soft texture, and bulkiness, and polyolefin fibers are preferred due to their cost and soft texture. Often used. As polyolefin fibers, those made of polyethylene and polypropylene are often used because they are relatively flexible, but nonwoven fabrics made of these fibers have the disadvantage of being weak in strength.

Furthermore, Japanese Patent Publication No. 10583/1983 discloses a heat-adhesive nonwoven fabric containing fiber-forming polymers having different melting points as a composite component, which provides a nonwoven fabric with satisfactory strength and texture. However, it had the drawback of lacking bulk.

(Problems to be Solved by the Invention) The present invention aims to solve the above-mentioned problems and provide a nonwoven fabric that has high strength, soft texture, and excellent bulkiness. be.

(Means for Solving the Problems) The present inventors have arrived at the present invention as a result of intensive research to solve the above problems. That is, one aspect of the present invention is a fiber aggregate composed of composite fibers containing polyolefin as a first component and polyester as a second component, in which at least a part of the first component of the composite fiber appears on the fiber surface, and An aggregate of composite heat-adhesive fibers continuous in the longitudinal direction of the fibers, where the number of crimps of the composite heat-adhesive fibers is 20/25 or less (eight) and the number of crimps is 40. The gist of the invention is a heat-adhesive nonwoven fabric containing 20% or more by weight of fiber group (B) having fibers/25 fibers or more.

The composite heat-adhesive fiber used in the heat-adhesive nonwoven fabric of the present invention is composed of a composite fiber made of polyolefin and polyester. Any polyolefin can be used as long as it has fiber-forming ability, such as polyethylene and polypropylene. That is, in addition to the above-mentioned homopolymers, copolymers such as linear low-density polyethylene copolymerized with α-olefin or the like, or blends of various polyolefin polymers may be used. On the other hand, polyesters whose main repeating units are ethylene terephthalate units are preferable in terms of strength and thermal stability, but a third component may be copolymerized within a range that does not reduce the thermal stability, strength, etc. Good too. As the third component, those commonly used as copolymerization components of polyester are used.

For example, dicarboxylic acids such as isophthalic acid and adipic acid are used as acid components, and diethylene glycol is used as diol components.

1,4-butanediol and the like are appropriately used depending on the purpose. Further, additives such as a matting agent, stabilizer 1 pigment, etc. may be appropriately mixed with the above polymer as required.

Next, the composite thermal adhesive fiber made of the two components.

Although any of the bimetal type, core-sheath type, seabird type, etc. can be used, the heat-adhesive fiber of the present invention utilizes the heat-adhesive property of the first component. It is necessary that they partially appear in the layer and are arranged continuously in the length direction. Furthermore, in order to impart bulkiness to a nonwoven fabric, which is an object of the present invention, among the fibers constituting the nonwoven fabric, a fiber group (A) having a low potential crimp ability with a number of crimps of 20/25 or less is used. It is necessary to contain 20% by weight or more of fibers consisting of fiber group (B) having a high potential crimp ability with a number of crimps of 40/25 or more. If the weight fraction of the fiber group (8) with low latent crimp ability is less than 20%, it is not preferable because the strength of the obtained nonwoven fabric decreases. On the other hand, if the weight fraction of the fiber group (B) with high potential crimp ability is less than 20%, the nonwoven fabric will have high strength but will have poor bulk and hard texture.

Here, the number of crimps of a fiber having latent crimp ability (hereinafter simply referred to as the number of crimps) is determined by the first-order method. First, a free shrink dry heat treatment was performed at a temperature below the melting point of the first component to develop crimps in the fibers, and the number of crimps in the fibers after this heat treatment was determined. This group of fibers with a high number of crimps has high bulkiness, but is generally susceptible to distortion due to heat and tends to be low in terms of strength. Therefore, in order to obtain a nonwoven fabric that meets the purpose of the present invention, it is necessary to use a combination of fiber groups having different numbers of crimps.

The heat-adhesive nonwoven fabric of the present invention has the above-mentioned constituent requirements, and can satisfy all of the properties of strength, bulkiness, and soft feel that have not been previously available.

The composite thermally bonded fiber used in the present invention can be manufactured using a conventionally known composite spinning apparatus, and any of bimetal type, core-sheath type, and seabird type can be used.

The cross-sectional shape of the composite heat-adhesive fiber is not limited to a circular shape, but may also be a triangular or quadrangular irregular cross-sectional shape, or a hollow cross-sectional shape. Note that the spun undrawn composite fibers were drawn using a conventionally known drawing device.

It can be produced by hot stretching at a temperature from room temperature to the melting point of the first component.

Next, the fiber group (^) and the fiber group (B) are mixed at a predetermined mixing ratio to obtain an aggregate of composite thermal adhesive fibers. First, the fiber group (A) and the fiber group (B) are mixed. ) may be used, and a card machine or the like used for forming a web of short fibers may be used, and there is no particular limitation. That is, one method is to separately spin and draw the fiber group (A) and the fiber group (B) and mix them in the form of a fabric that is cut into a predetermined fiber length. Furthermore, rather than performing spinning and drawing separately to obtain fiber groups with different numbers of crimps, co-spinning is performed using the same nozzle by combining polymer viscosities, copolymerization polymers, etc.

It is also possible to obtain materials with different numbers of crimps by utilizing differences in stretchability due to differences in polymer composition. Any of these can be used to produce the nonwoven fabric of the present invention.

Next, the aggregate of the composite thermally adhesive fibers is made into a non-woven fabric by thermally fusing the low melting point component (polyolefin component) of the composite fibers. As a heat fusion machine.

Any machine such as a dryer such as a hot air dryer, a suction drum dryer, or a Yankee dryer, or a hot roll such as a flat calendar roll or an embossing roll can be used.

(Function) The thermoadhesive nonwoven fabric of the present invention satisfies all of the following requirements: 1) strong strength, bulkiness, and soft texture;
The present inventors conjecture as follows. In other words, the heat-adhesive nonwoven fabric of the present invention has a fiber group (A) with a small number of crimps (both 20/251n or less) and a fiber group (A) with a number of crimps of 40/725
It is composed of N or more fiber groups (B), and each fiber group has a shared role, so that the object of the present invention can be achieved. Fiber group with 20 crimps/25w or less (
A) supports the strength of nonwoven fabric.

On the other hand, fiber group (B) with a number of crimps of 40/251 cm or more gives bulkiness and a soft texture, and in order to share their roles, it is necessary to calculate the weight of the fibers constituting the nonwoven fabric as a proportion of each fiber group. A weight fraction of 20% or more is required for each. For this reason, more than 40% of the nonwoven fabric layer is composed of two types of fiber groups with significantly different crimp pitches, and this large difference in crimp pitch has the effect of reducing set in repeated compression. It also has the advantage that its bulkiness is not impaired during use.

(Example) The present invention will be explained in more detail below with reference to Examples.

In addition, the physical property values measured in the examples were evaluated by the following method.

(1) Number of crimp After developing crimp, it was measured according to JIS L-1015.

(2) Strength of nonwoven fabric Measured according to the JISL-1096 strip method at a width of 25 mm, a length of 100 u+, and a tensile speed of 1001 m/min.

(3) Texture of nonwoven fabric A sensory test was conducted and evaluated by five panelists. The evaluation criteria are as follows.

〇−・−・・− All 5 people judged it to be soft △・−−−m−
- 3 Å or more was judged as soft × - - - - 3 or more people judged as lacking in softness (4) Bulkyness of non-woven fabric After stacking 20 square pieces of non-woven fabric of 10 cm x 10 cm.

The height when a load of 20 g was applied to the entire surface was measured and expressed in volume per 1 g of nonwoven fabric, and it was judged that the larger the value, the higher the bulkiness.

[Manufacture of crimped fiber 1] High-density polyethylene (HDPE) with a melt index of 20 g/10 minutes and a melting point of 130°C as measured by the method of ASTM D-1238 (E) is used as the first component (sheath component), Polyethylene terephthalate with an intrinsic viscosity [η) = 0.68 was used as the second component (core component), a spinneret with a pore diameter of 0.5+n and a number of holes of 429 was used, and the melting temperature of the first component was 250.
°C, the melting temperature of the second component is 285 °C, and the spinning speed is 1100 °C.
An undrawn yarn was obtained under conditions of m/min and a core/sheath composite ratio of 50:50. Next, the obtained undrawn yarn was drawn under various drawing conditions, and then cuffed to a fiber length of 51 to produce fabrics having various latent crimp abilities. Then, 125℃×
A free shrink heat treatment was performed for 15 minutes to obtain a crimped cloth.

The number of fibers in the obtained crimped cloth is 3 to 19/2
5 fin fiber groups (8), number of crimps 42-65/25++m
It consisted of three types of fibers: the fiber group (B) and the fiber group (C) with 23 to 38 crimps/25 crimps, and each fiber group had a short fiber fineness of 2 denier.

[Manufacture of crimped fiber 2] The first component was polypropylene (PP), which had a melt index of 22 g/10 minutes as measured by the method of ASTM 04238 (L) and a melting point of 160°C, but all other components were crimped fibers. Crimped fiber 2 was produced in accordance with the production of Example 1. The crimp development conditions were a free shrink heat treatment at 155° C. for 15 minutes to obtain a crimp fabric. The number of fiber groups of the obtained crimped cloth was 2 to 20/25 fiber groups (A), 43 to 59
pieces/25 dragon fiber group (B) and 24-39 pieces/251n
Three types of fiber group (C) were obtained. The short fiber fineness and fiber length of each fiber were 2 denier and 51n+.

Examples 1-6. Comparative Examples 1 to 3 Using crimped fiber 1, each fiber group was mixed to obtain an aggregate for forming a nonwoven fabric. At this time, after varying the proportions of each fiber group, this aggregate was fed to a carding machine and the fabric weight was 40.
After forming a web of g/m2, it was dried at a temperature of 1
A nonwoven fabric was produced by heat treatment at 50°C. The performance of the obtained nonwoven fabric was evaluated and the results are shown in Table 1. As is clear from the table, nonwoven fabrics containing 20% or more of vA fiber group (A) and fiber group (B) each have good tensile strength, bulkiness, and thermal adhesiveness with a soft texture. It was a nonwoven fabric. On the other hand, in the comparative examples, either the fiber group (A) or the fiber group (B) was less than 20%, or both were less than 20%, and the fiber group (A) was small.

It is superior in terms of bulk and texture, but inferior in terms of strength.
On the other hand, those containing less fiber group (B) were superior in terms of strength, but inferior in terms of bulk and texture.

Table 1 Examples 7-9. Comparative Examples 4 to 6 Using crimped fiber 2, each fiber group is mixed to form an aggregate for forming a nonwoven fabric, the mixing ratio is varied as shown in Table 2, and this aggregate is made into a card. After feeding it into a web with a basis weight of 40 g/m'', a nonwoven fabric was produced using a single rotation dryer at a heat treatment temperature of 180°C.The performance of the obtained nonwoven fabric was evaluated, and the results are shown in Table 2. As is clear from the table, when either or both of fiber group (A) and fiber group (B) was less than 20%, a nonwoven fabric with satisfactory performance could not be obtained. When the fiber group (A) was less than 20%, it was excellent in terms of bulk and texture, but only a low strength nonwoven fabric was obtained.On the other hand, when the fiber group (B) was less than 20% Case 1 was excellent in terms of strength, but inferior in both texture and bulk.

Table 2 (Effect of the invention) The thermoadhesive nonwoven fabric according to the present invention is fiber group (A).

It consists of a fiber aggregate containing two types of heat-adhesive fibers of fiber group (B) with different numbers of crimps, each in a weight fraction of 20% or more. A nonwoven fabric made of a fiber aggregate that satisfies both quality and performance,
The obtained nonwoven fabric has a soft feel, excellent strength, and high bulkiness, so it can be widely used as covering paper for disposable diapers, sanitary products, etc.

Patent applicant: Nihon Ester Co., Ltd. Agent Yuzo Kodama

Claims (1)

[Claims] (1) Polyolefin is the first component, polyester is the second component
A fiber aggregate composed of composite fibers as a component, in which at least a part of the first component of the composite fibers appears on the fiber surface, and is continuous in the longitudinal direction. Therefore, the number of crimps of the composite thermal adhesive fiber is 20/
Fiber group (A) of 25 mm or less and number of crimps is 40/25 m
A heat-adhesive nonwoven fabric containing 20% or more by weight of each fiber group (B) of m or more.