JPH02182957A - Polyester nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain a nonwoven polyester fabric having soft texture and excellent stretchability and suitable for sports wear, sanitary material, etc., by mixing a specific conjugate staple fiber and a specific hot-melt staple fiber at a specific ratio and subjecting the mixture of heat-bonding the crimp-developing treatment. CONSTITUTION:Two kinds of polyethylene terephthalate-base polymers having an intrinsic viscosity difference of 0.15-0.25 and crystallization initiation temperature difference of >=40 deg.C are subjected to side-by-side conjugate spinning, drawing, application of crimp and cutting to obtain conjugate staple fibers. The polymer having high intrinsic viscosity contains 6-12mol% of isophthalic acid as copolymerized unit. The staple fibers are mixed with hot-melt staple fibers composed of a low-melting polyethylene terephthalate-base polymer at a ratio of 60:40-90:10 and the obtained web is subjected to heat-bonding and crimp- developing treatment (preferably heat-treating at 130 deg.C and then at 170 deg.C) to obtain the objective nonwoven polyester fabric.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a polyester nonwoven fabric that is flexible and has excellent elasticity and is suitable for use in sports clothing, materials, bedding, and the like.

[Prior art and problems to be solved by the invention] Nonwoven fabrics have been manufactured from various materials in the past, and short fibers are mixed with heat-adhesive fibers to form a web, which is then bonded by heat treatment to form a nonwoven fabric. The method is also known to Kaichi.

In particular, there is an increasing demand for nonwoven fabrics with excellent elasticity for use in sports clothing and materials, and efforts are being made to develop nonwoven fabrics that meet these demands.

As a method for manufacturing a nonwoven fabric with excellent elasticity, it is preferable to use high A short fibers that exhibit crimp properties, and a method for manufacturing such short fibers is to bond two types of polymers with different shrinkage rates side-by-side. is a common manufacturing method.

As polymers with different shrinkage rates, polymers with different intrinsic viscosities are usually used.When two types of polymers have the same composition, the shrinkage rates are controlled by making a difference in molecular weight and using the difference in crystallization rate. , which causes crimping. This is an application of the phenomenon that when the molecular weight is low, the crystallization rate is fast, so the shrinkage rate during heat treatment is low, and when the molecular weight is high, the crystallization rate is slow, so the shrinkage rate during heat treatment is high. .

Therefore, when trying to obtain high crimp, it is desirable to make the difference in intrinsic viscosity between the two polymers as large as possible.
However, as the difference in intrinsic viscosity increases, knealing becomes more likely to occur at the exit of the spinning nozzle, which naturally limits the difference in intrinsic viscosity that can be obtained, and also limits the degree of crimp development in the fibers.

Various methods have been proposed to improve this problem, including increasing the intrinsic viscosity difference but increasing the melt viscosity difference, that is, adding additives to lower the melt viscosity of high intrinsic viscosity polymers. However, an effective table method that satisfies practical performance has not yet been found.

The present invention provides a nonwoven fabric that is flexible and has excellent elasticity by using polyester composite fibers that have sufficient crimp performance while keeping the difference in intrinsic viscosity within a range that allows melt spinning.

[Means to solve problems]

The present invention is a composite fiber in which two types of polyethylene terephthalate polymers having an intrinsic viscosity difference in the range of α15 to IIL25 are joined in a side-by-side manner, and the polymer on the higher intrinsic viscosity side absorbs isophthalic acid by 6 to 12 molt. Composite short fibers made of a polymerized polyethylene terephthalate-based polymer and in which the crystallization initiation temperatures between the two polymers differ by 40°C or more, and heat-adhesive short fibers made of a polyethylene terephthalate-based low melting point polymer are mixed in a ratio of 60:40 to 90.
: Polyester nonwoven fabric that has been mixed at a ratio of 100 and subjected to thermal adhesion and crimp development treatment.

To explain the present invention in more detail, in the composite short fibers used in the present invention, the difference in intrinsic viscosity between two types of polymers joined side-by-side must be in the range of l115 to α25. In other words, as mentioned above, the larger the difference in intrinsic viscosity between the two types of polymers, the more advantageous it is to developing crimp.
If the intrinsic viscosity difference exceeds L25, needling occurs at the nozzle outlet during spinning, resulting in significantly poor spinning stability; When terephthalate is used, even if the intrinsic viscosity difference is kept within the range of (L15 to a, 25), the degree of crimp development does not become very high.

Therefore, in the present invention, by keeping the intrinsic viscosity within the range of 015 to α25 and increasing the difference in crystallization initiation temperature between both polymers, the crystallization temperature is low b1, that is, crystallization A high rate of crystallization of the polymer to keep the JII yield within a small range, and a high crystallization temperature of the polymer
By making the polymer substantially amorphous, it exhibits a high shrinkage rate, and the difference in shrinkage rate makes it possible to obtain extremely large crimp. However, if polymers of the same composition are used and the intrinsic viscosity is simply changed, the crystallization initiation temperature difference cannot be greater than 40° C. within the range of 115 to (L25).

Therefore, in the present invention, by using a polyethylene terephthalate-based polymer copolymerized with 8 to 12% isophthalic acid as a polymer on the high intrinsic viscosity side, the crystallization initiation temperature is increased to 40 This makes it possible to have a difference of more than ℃.

The higher the copolymerization ratio of isophthalic acid, the more effective it is, but copolymerization of isophthalic acid also lowers the melting point of the silimer, so if the copolymerization ratio exceeds 12. Undesirable. In addition, when the copolymerization ratio is 6, it is not possible to obtain substantially large crimp. The temperature at which the nonwoven fabric of the present invention is heat treated is preferably 130 to 18'0°C.

This is because at temperatures below 150°C, the polyester with a lower intrinsic viscosity does not crystallize, making it impossible to increase the difference in shrinkage rate between the two polymers, and at temperatures above 180°C, both polymers fully crystallize. It is not possible to increase the difference in shrinkage rate. Also, from the viewpoint of thermal decomposition, the range b is preferably 18 (Ic or less).

The heat treatment may be carried out in one stage at a temperature of 130 to 180°C, but it is preferable to perform the first heat treatment at a low temperature that allows bonding of the thermoadhesive fibers, and then heat the composite fibers at a high temperature. It is desirable to allow free shrinkage of the composite fibers.This is because if high-temperature heat treatment is performed in only one stage, adhesion of the thermally bonded fibers and free shrinkage of the composite fibers will proceed at the same time, causing shrinkage spots and impairing the aesthetics. .

From the viewpoint of the texture of the nonwoven fabric, it is preferable that the blending ratio of heat-adhesive fibers is small, but if it is less than 104, a matrix of heat-adhesive fibers cannot be formed in the web during the first heat treatment. If it exceeds 40, the product will have a hard texture, which is not practical.

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

〔Example〕

Polyethylene terephthalate with an intrinsic viscosity (+y) of 0.65 is used as one component, and polyethylene terephthalate-based polymers with various copolymerization ratios of [wa] and isophthalic acid are used as other components, and composite spinning is performed in a side-by-side type.
After stretching at a temperature of 60°C and a magnification of 4.06 times, constant length meditation and theory was performed at 130°C, mechanical crimp was applied, and cutting was performed to obtain a single yarn fineness of 2.5.
Composite short fibers with a denier and a fiber length of 51 m were obtained. Two polyethylene terephthalate heat-adhesive short wires ia (50 (1X51111)) having a melting point of 120'C were added to this composite short fiber.
0 to form a carded web, which was subjected to a first stage heat treatment at 150°C in a rotary drum dryer, followed by a second stage heat treatment at υ170°C in a hot air circulation type dryer to obtain a carded web with a basis weight of 40'. A dry nonwoven fabric of 1/m" was obtained.

The composite spinning stability and the number of crimps of composite short fibers are shown in the table below.

Note that &1 to 4 and 6 are comparative examples, and cliff 5 is an example.

By using it, a nonwoven fabric with excellent flexibility and stretchability can be obtained, and its industrial value is extremely large.

[7] Intrinsic viscosity Ta” = x Peak temperature at which crystallization starts measured at D80 PA-Isophthalic acid copolymerization ratio

Claims (1)

[Claims] It is a composite fiber in which two types of polyethylene terephthalate polymers having an intrinsic viscosity difference in the range of 0.15 to 0.25 are joined side-by-side, and the polymer on the higher intrinsic viscosity side contains 6 to 12 mol% of isophthalic acid. Composite short fibers made of a copolymerized polyethylene terephthalate-based polymer and in which the crystallization initiation temperatures between the two polymers differ by 40°C or more, and heat-adhesive short fibers made of a polyethylene terephthalate-based low melting point polymer are 60:40 to 90: A polyester nonwoven fabric that is mixed at a ratio of 1:10 to 10:1 and is thermally bonded and crimped.