JPS62250260A - Nonwoven fabric and its production - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a water-absorbent and flexible nonwoven fabric using heat-adhesive fibers as a binder, and a method for producing the same.

<Prior art> Conventionally, methods for manufacturing nonwoven fabrics have been known in which undrawn polyester fibers, bimetallic or core-sheath composite fibers of polyethylene and polypropylene or polyester are used as heat-adhesive fibers, and fibers are bonded together. .

<Problems to be solved by the invention> In this case, thermally adhesive fibers are extremely effective as binders, but since they are all hydrophobic, they are When the ratio of adhesive fibers is increased, the water absorbency of the product decreases even if the main fibers of the resulting nonwoven fabric are treated with water absorbency.

In recent years, it has become desirable for products using such heat-adhesive fibers as a binder to have sufficient water absorbency, and the present invention provides a novel nonwoven fabric that can meet these demands. This is what we intend to provide.

Means for Solving the Problems> The present invention provides a nonwoven fabric in which main fibers are thermally bonded by low-temperature melting or softening components of heat-adhesive fibers, in which the fibers are three-dimensionally entangled and at least the heat-adhesive fibers are thermally bonded. or a nonwoven fabric characterized in that a water-absorbing substance is present on at least a part of its melted or softened surface, and the nonwoven fabric is partially attached to the main fiber and the surface in advance at a thermal bonding temperature to substantially A mixed fiber web with heat-adhesive fibers to which a water-absorbing substance that does not cause thermal decomposition or sublimation is added is fluidly entangled to entangle each fiber three-dimensionally, and then the entangled web is heat-treated. , a method for producing a nonwoven fabric characterized by thermally melting or softening a low-temperature melting or softening component of heat-adhesive fibers to thermally bond the fibers; A water-absorbing substance that does not substantially undergo thermal decomposition or sublimation at the heat-bonding temperature is applied during or before or after the heat-bonding temperature, and then heat-treated to melt or soften the low-temperature melting or softening components of the heat-bonding fiber. A method for producing a nonwoven fabric characterized by thermal bonding between fibers.

In the present invention, various types of fibers can be used as the main fiber, but in particular, natural fibers having hydrophilic or water-absorbing properties,
Regenerated fiber 1 Synthetic fiber is effective.

As for hydrophilic synthetic fibers, in the case of those made of hydrophobic polymers, a water-absorbing substance is added to at least the surface, preferably a water-absorbing substance that does not substantially thermally decompose or sublimate at the bonding temperature of the thermal adhesive fiber. Preferably, the fibers have a microporous structure in the surface layer or the entire fiber. of course.

Those made of hydrophilic polymers such as polyvinyl alcohol and saponified ethylene-hinyl acetate copolymers do not require the above-mentioned processing.

In addition, the heat-adhesive synthetic fibers referred to in the present invention include:

Polymers that melt or soften entirely at low temperatures, such as polyethylene, polypropylene, saponified products of ethylene-vinyl acetate copolymers, fibers made of copolyester, or polymers that melt or soften at low temperatures and their melting or softening temperatures. The target is conjugate fibers obtained by composite or mixed spinning of polymers with a high carbon content and in which at least low-temperature melting or softening components are exposed.

Examples of the composite fiber include bimetal type, core-sheath type (including multicore type), and seabird type. Furthermore, undrawn polyester fibers can also be effectively used as the heat-adhesive synthetic fibers.

The nonwoven fabric of the present invention is one in which the main fibers and heat-adhesive fibers are three-dimensionally entangled, and the fibers are thermally bonded by low-temperature melting or a softening component (adhesive component) of the heat-adhesive fibers. The biggest feature is that at least a part of the surface of the heat-adhesive fiber or its melted or softened part is attached with a substance that imparts water absorption properties, and more preferably the main fiber is also hydrophilic or water-absorbing. The point is that it has the following.

The substance imparting water absorption properties is produced by melting the low-temperature melting components or softening the softening components of the heat-adhesive fibers by heat-pressing a web-like material formed by mixing heat-adhesive fibers and main fibers to form a material between the fibers. At least the water-absorbing substance must remain in the product after it is adhered. Therefore, the water-absorbing substance has an affinity for the heat-adhesive fiber.

The material should also be selected taking into account the washing resistance and the durability of the water flow path as described below.Generally, it is selected from polymers containing water-absorbing components, and at the heat bonding temperature, it is substantially heat-resistant. There is no decomposition or sublimation.

As such a substance, a polycondensate of polyethylene glycol and terephthalic acid is particularly preferable, and has a structure as shown by the following formula, for example. These are 5R1000 (Takamatsu Yushi), Permarose T (I.

It is commercially available under the names such as C,1,).

Rmo0OC-Ql-COOCH2CH2+0-Rj~-
1-5-R' The amount of these substances attached to the fibers is determined appropriately depending on the type, but 0.05 to 3% (weight to fiber is effective. If it is less than 0.05%, the water absorption of the product is insufficient. If the number of adhesive fibers exceeds 3, the low-temperature melting components of the adhesive fibers will melt, which may not only interfere with adhesion but also cause slime on the product. For example, in the case of 5R1000 (Takamatsu Yushi), the adhesion amount is preferably about 0.1 to 1%.The water-absorbing substance is also used to impart water-absorbing properties to the main fiber.

One of the methods for producing the nonwoven fabric of the present invention is to prepare a mixed web of heat-adhesive fibers to which at least the above-mentioned water-absorbing substance has been applied in advance and main fibers, preferably hydrophilic or water-absorbing fibers, by fluid entanglement. In this method, the fibers are entangled in a three-dimensional manner by liquid flow entanglement, and then heat-treated by means such as hot pressing, and the fibers are bonded by heat melting or a softening component of the heat-adhesive fiber.

In this case, it is extremely efficient to apply the water-absorbing substance to the fibers continuously in the fiber manufacturing process, for example, in the oiling process after spinning, but it may also be applied in the form of tow or cotton. The adhesion temperature to the heat-adhesive fiber is at least 1 from room temperature to the melting temperature of the low-melting component of the fiber.
It should be carried out in a temperature range below 0°C.

Another method for producing a nonwoven fabric of the present invention is to fluidly entangle a mixed web of thermoadhesive fibers and main fibers to three-dimensionally entangle the fibers, during or before or after this entanglement process. A water-absorbing substance is added to the fibers, followed by heat treatment to bond the fibers together.

The water-absorbing substance is applied by dispersing or dissolving it in the water used for the entanglement treatment, or by dipping or showering after the entanglement treatment. It is desirable to add a substance. If applied before entanglement, a drying step is required.

These manufacturing methods require fluid entanglement of the web, which allows the fibers to become three-dimensionally entangled, resulting in a nonwoven fabric that is more flexible than a mixed web that is simply bonded between the fibers using heat press, etc. It can be done.

In particular, when using the method of the present invention to produce products with a soft texture, such as disposable diaper 7-aging material, sanitary napkins, and wet tissues, so-called kneading, which entangles the web with water jets, is performed. After inserting it, it is effective to thermally bond it using a heat press or the like.

In addition, since hydroentanglement utilizes a high-pressure water stream, ordinary oil agents (which generally have a hydrophilic effect to impart an antistatic effect) are removed from the fiber surface without any stains, creating a water absorption effect within the product. is not retained.

For this reason, when a water-absorbing substance is applied to heat-adhesive fibers or the like in advance and a web made of these is hydroentangled, it is necessary to use a durable water-absorbing substance as described above.

Furthermore, in order to simplify the process in manufacturing the nonwoven fabric of the present invention, it is better to apply a water-absorbing substance to the fibers in advance before forming the web.

Effects and Effects> According to the present invention, even when the mixing ratio of heat-adhesive fibers is high, the nonwoven fabric does not have sufficient water absorbency and is extremely flexible, making it extremely difficult to use. Expanded. For example, in the case of a disposable diaper, when an infant urinates several times a night, the urine passes through the 7-acing material and is absorbed into the absorbent polymer in the diaper body, but the surface always feels dry. It's better. In general, 7 Acing has a high mixing ratio of heat-adhesive fibers to sufficiently suppress fluff, and lacks water absorbency, so it can be used in cases where the amount of urine increases.

It is unavoidable that the temperature of the urine will accumulate on the surface, which will have a negative effect on the baby's skin, and the texture will become hard and uncomfortable.

However, when the nonwoven fabric of the present invention is used in 7-Acing, even if the mixing ratio of heat-adhesive fibers is increased and the fluff is sufficiently suppressed, the nonwoven fabric can have high water absorption and a soft texture. After adhesion, the durability of water absorption is high, probably because the water absorbing substance enters or is mixed with the low temperature melting component.

Example 1 A water-absorbing material (SRloo
o (manufactured by Takamatsu Yushi)] 7t3dX51m
core-sheath type adhesive fiber (4), the same fiber (B) with no water-absorbing substance added, 2dX with t-0.5% of the same water-absorbing substance added
51ml/Jl of polyethylene terephthalate fiber (Q,
Polyethylene terephthalate fiber 0 to which no water-absorbing substance is added is prepared. The adhesion temperature of the copolymerized polyester (low temperature melting component) in fibers A and B is 140'C. A predetermined amount of the water-absorbing substance is attached to the fiber after it has been stretched, and then
It was dried in a hot air dryer at 80°C.

Using these fibers A and B as binder fibers and C1D as the main fiber, nonwoven fabrics having a basis weight of 309/Ml and a thickness of 0.9 mm were produced at the respective combination mixing ratios as shown in Table 1. The nonwoven fabric was produced by mixing each fiber, forming a silanip with a card, entangling the fibers with a high-speed water stream, and then heating and roller pressing at 140°C. The water absorbency and flexibility of the obtained nonwoven fabric are shown in Table 1.

Table 1 1) Add 1 drop of Congo Red 0.2% solution from a height of 21 (
0.4 cc) is added dropwise and the time required for it to be absorbed by the sample is shown.

2) After repeating the process of passing 15 cc of water and drying 5 times, measure using method 1).

5) Measurement of degree of bending of nonwoven fabric by cantilever method.

Comparative Example 1 In the case of nonwoven fabric configuration (4)+(Q), a nonwoven fabric was produced without performing high-speed hydroentanglement treatment under the same conditions.

The flexibility in this case was 55j1m, and the texture was paper-like and hard.

Example 2 A nonwoven fabric was manufactured according to Example 1 using B and D shown in Example 1. At that time, after being entangled with a high-speed water stream, a water-absorbing substance (SRloooo) (Takamatsu Yushi Tsuki) was attached to about 0.4 yen by dipping-squeezing method, and pressed with a heated roller at 140°C. A nonwoven fabric was made.The water absorption performance is shown in Table 2.

Table 2

Claims (1)

[Scope of Claims] 1) A nonwoven fabric in which the main fibers are thermally bonded by a low-temperature melting component or a softening component of heat-adhesive fibers, in which each fiber is three-dimensionally entangled and at least the heat-adhesive fibers or their melting or softening components. A nonwoven fabric characterized in that a water-absorbing substance is present on at least part of the surface of the nonwoven fabric. 2) The nonwoven fabric according to claim 1, wherein the main fibers are hydrophilic fibers or synthetic fibers imparted with water absorbency. 3) A mixed fiber web of the main fiber and a heat-adhesive fiber to which a water-absorbing substance that does not substantially thermally decompose or sublimate at the heat-bonding temperature has been partially applied to the surface is fluidly entangled to form each fiber three-dimensionally. After being entangled, the entangled web is heated,
A method for producing a nonwoven fabric characterized by thermally melting or softening a low-temperature melting or softening component of heat-adhesive fibers to thermally bond the fibers. 4) A method for producing a nonwoven fabric according to claim 3, which employs hydroentanglement as the fluid entanglement means. 5) The method for producing a nonwoven fabric according to claim 3 or 4, wherein the main fiber is a hydrophilic fiber or a synthetic fiber imparted with water absorbency. 6) A patent claim in which the heat-adhesive fiber is a bimetallic composite fiber consisting of a low-temperature melting or softening component and another component, a core-sheath composite fiber having a low-temperature melting or softening component as a sheath, or a mixed spun fiber of both components. A method for producing a nonwoven fabric according to item 3, item 4, or item 5. 7) The method for producing a nonwoven fabric according to any one of claims 3 to 6, wherein the heat-adhesive fibers are undrawn polyester fibers. 8) A water-absorbing substance that does not substantially thermally decompose or sublimate at the thermal bonding temperature is added to the mixed web of the main fiber and the heat-adhesive fiber during or before or after fluid entanglement, and then heat-treated. A method for producing a nonwoven fabric characterized by melting or softening a low-temperature melting or softening component of adhesive fibers and thermally bonding the fibers. 9) A method for producing a nonwoven fabric according to claim 8, which employs hydroentanglement as the fluid entanglement means. 10) The method for producing a nonwoven fabric according to claim 8 or 9, wherein the main fiber is a hydrophilic fiber or a synthetic fiber imparted with water absorbency. 11) A patent claim in which the heat-adhesive fiber is a bimetallic composite fiber consisting of a low-temperature melting or softening component and another component, a core-sheath composite fiber having a low-temperature melting or softening component as a sheath, or a mixed spun fiber of both components. A method for producing a nonwoven fabric according to Item 8, Item 9, or Item 10. 12) The method for producing a nonwoven fabric according to any one of claims 8 to 11, wherein the heat-adhesive fibers are undrawn polyester fibers.