JPH01148859A - Extensible nonwoven fabric - Google Patents

Abstract

PURPOSE: To obtain a stretchable non-woven fabric having excellent stretchability and elongation recovery and suitable for bandages, the base fabrics of poultices, etc., by blending conjugate fibers having different shrinking properties, respectively, in a constant ratio and then fusing the adhesive component of the conjugate fibers having the low shrinking property to fix the mutual contact points of the fibers. CONSTITUTION: The stretchable non-woven fabric is obtained by blending (A) 90-50 wt.% of highly shrinkable conjugate fibers with (B) 10-50 wt.% of low shrinkable and thermally fusible conjugate fibers and then fusing the fusible component of the component B to fix the mutual contact points of the fibers. It is preferable that the melting point of the component constituting the component A is higher by >=5 deg.C than the melting point of the fusible component of the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a nonwoven fabric with excellent elasticity used for base fabrics of poultices, bandages, etc.

[Prior art and its problems]

The nonwoven fabric, which is made by bonding the fibers together by thermally fusing the low melting point components of thermoadhesive composite fibers made of two types of thermoplastic resins with different melting points, is hygienic and smooth to the touch. Because of these characteristics, it is often used as a surface material for masks and paper diapers.

As a method of imparting stretchability to such a nonwoven fabric, a method is known that uses heat-adhesive composite fibers whose fibers are crimped during heat treatment for heat-sealing. However, this method has problems such as shrinkage of the fibers due to crimping during heat treatment, resulting in non-uniform thickness and density of the nonwoven fabric.

[Means to solve the problem]

As a result of intensive research in order to obtain a homogeneous nonwoven fabric with excellent elasticity, the present inventors made a web of mixed fibers of a highly shrinkable conjugate fiber figure and a low shrinkage and thermally bondable conjugate fiber tBl,
The present invention was completed based on the knowledge that the desired objective could be achieved by fixing the contact points between the fibers by fusing the adhesive component of the composite fiber (B).

In the present invention, high shrinkage means when the shrinkage rate of the fibers due to crimping during heat treatment described below exceeds 40 parts, and low shrinkage means when the shrinkage ratio is 20 parts or less. do.

Low-shrinkage and heat-adhesive conjugate fiber (B
l is two types of thermoplastic resins with melting points different by 20°C or more, and the thermoplastic resin with the lower melting point (hereinafter sometimes referred to as the adhesive component) occupies 50 or more parts of the fiber surface in a parallel or parallel type. It is a sheath-core type composite spun yarn.In order to achieve low shrinkage, it is best to use the sheath-core type, but even if it is a parallel type, the spinning and drawing conditions must be selected (for example,
2-37097 and Japanese Patent Publication No. 52-4653) or by sufficient annealing treatment. If the content of composite fiber (Bl) in the mixed fiber is less than 10% by weight, there will be insufficient adhesion points between the fibers, resulting in insufficient strength and elongation recovery rate, and if it exceeds 50% by weight, there will be too many adhesion points, resulting in poor elongation of the nonwoven fabric. It is not desirable because of the lack of.

The highly shrinkable composite fiber used in the present invention is polyester/
High-density polyethylene, propylene homopolymer/propylene/ethylene copolymer, nylon 66/nylon 6, etc.
It is obtained by composite spinning two types of thermoplastic resins with different properties in a parallel type or an eccentric sheath-core type. The shrinkage rate varies depending on the spinning and drawing conditions, but in general, high shrinkage can be achieved by drawing 1.5 to 2.5 times at a low temperature. However, in the heat treatment described below, the contact points between the fibers are replaced with composite fibers (B
), the thermoplastic resin used for the composite fibers is selected to have a melting point 5° C. or more higher than that of the adhesive component.

If the content of composite fibers in the mixed fibers is less than 50% by weight, the resulting nonwoven fabric will have poor elasticity and insufficient elongation recovery.
If the weight ratio exceeds 0, shrinkage spots will occur, which is not preferable.

In the present invention, other fibers may be mixed and used as long as the contents of the composite fibers and the composite fibers CB+ do not exceed the above-mentioned contents. Other such fibers include
Any fiber may be used as long as it does not shrink or deteriorate due to the heat treatment described below, and examples thereof include natural fibers such as cotton and wool, and synthetic fibers such as rayon, nylon, polyester, and polyolefin. The mixture of the above fibers is formed into a web having a desired basis weight using a known device such as a card machine or a random univer, and the composite fiber (high melting point resin of Bl) is heated at a temperature higher than the melting point of the adhesive component (low melting point resin of Bl). The composite fiber (A) is heat-treated to form a non-woven fabric at a temperature lower than the melting point of both components.The heat treatment can be performed by a known method such as infrared heating, a hot air dryer, or a heated roll.

〔Example〕

The present invention will be explained in more detail with reference to Examples and Comparative Examples. The test methods used on each side are as follows.

Shrinkage rate: A parallel web of 25° each in length and width is heated in a hot air oven at the processing temperature for 5 minutes, and the length in the longitudinal direction (al) after heating is measured, and determined by (1-a/25) x 100 = shrinkage rate.

In accordance with the tensile test method of Initial Elongation JIS L 1085 (Nonwoven fabric test method), a load-elongation curve was drawn using a test piece with a width of 5 cnL and a length of 20 degrees at a gripping interval of 10 cIrL and a tensile speed of 10 cm/min. , the elongation when the load becomes 200 g is defined as the initial elongation.

Elongation recovery rate According to JIS L 1096 (-patterned fabric test method) elongation recovery rate measurement method (constant length method) K, width 5 (m% length 20cm)
Clamp the upper end of the rrL test piece and
Mark the WL interval, stretch it until the distance between the marks is 12 degrees, leave it as it is for 1 minute, remove the weight, measure the length (L) between the marks after 3 minutes, and measure (6-L/2) x 100. = Determined by recovery rate.

Texture A sensory test was conducted by five panelists, and if all of them judged it to be soft, it was ○, if three or more people judged it to be soft, it was △, and if three or more people judged it to be lacking in soft feel. Display the cases with an ×.

Uniformity: A transparent glass plate (thickness: 5 mvt%, length: 10 c!rL) was placed on a nonwoven fabric (10 α in length and width) on a black mount, and when compressed by the weight of the glass, it had a diameter of 1 m.
Measure the number of holes above, and if the number of holes is 0, ○, 1~
Two items are represented by Δ, and three or more items are represented by ×.

Examples 1 to 7, Comparative Examples 1 to 6 Using the 5m type fibers shown in Table 1, webs with various mixing ratios shown in Table 2 were made and heat-treated in a hot air oven for 3 minutes to obtain nonwoven fabrics. I got it. The basis weight, heat treatment temperature, and physical properties of the nonwoven fabric are also shown in Table 2.

Table 1 Composite fiber (1): Ethylene-propylene copolymer (melting point 138°C) and crystalline polypropylene (melting point 165°C) are spun in parallel at a composite ratio of 50,150, and
．． Single yarn fineness 3 denier obtained by drawing 7 times, fiber length 51
My composite fiber.

Composite fiber (2): High density polyethylene (melting point 132°C)
and crystalline polypropylene (melting point 165°C) at a composite ratio of 5
A composite fiber with a single fiber fineness of 3 denier and a fiber length of 51 mm obtained by parallel composite spinning at 0150 and drawing 4 times at 30°C.

Composite fiber (3): The sheath component is ethylene/vinyl acetate copolymer (melting point + 3°C), the core component is crystalline polypropylene (melting point 165°C), and composite spinning is carried out into a sheath-core type at a composite ratio of 50150, and the fiber is spun at 80°C. Composite fiber with a single fiber of 3 denier and a fiber length of 51 strands obtained by drawing 5 times.

Composite fiber (4): Crystalline polypropylene (melting point 165°C
) and high-density polyethylene (melting point: 132°C) were composite-spun in parallel at a composite ratio of 50,150 so that the high-density polyethylene occupied 66 divisions of the diagonal of the yarn break, and stretched 4 times at 100°C. A composite fiber with a single yarn fineness of 3 denier and a fiber length of 51 m.

PP fiber: A fiber with a single fiber fineness of 3 denier and a fiber length of 51 m obtained by spinning crystalline polypropylene alone.

As is clear from the results shown in Table 2, in the nonwoven fabric of the present invention, the contact points between fibers are firmly bonded by the low melting point resin of composite fibers (Bl) through heat treatment, and the composite fibers are Since only the fibers tend to shrink, appropriate stress acts between the fibers, resulting in excellent stretchability and stretch recovery.

that's all

Claims (2)

[Claims] (1) Contains 90 to 50% by weight of a highly shrinkable conjugate fiber (A) and 10 to 50% by weight of a low-shrinkage, heat-adhesive conjugate fiber (B), and the contact points between the fibers are the conjugate fiber ( A stretchable nonwoven fabric characterized in that it is fixed by fusing the adhesive component of B). (2) The melting points of the components constituting the high-shrinkage conjugate fiber (A) are each 5° C. or higher higher than the melting point of the adhesive component of the low-shrinkage and heat-adhesive conjugate fiber (B). A stretchable nonwoven fabric according to claim 1.