JPS63270813A - Hot-melt composite binder fiber - Google Patents

Abstract

PURPOSE:To obtain the titled binder fiber having excellent adhesivity, by combining a specific low-melting copolyester with a high-melting polymer having a crystal melting point above a specific level in a manner that the copolyester occupies at least a part of the surface of the produced fiber. CONSTITUTION:The objective binder fiber capable of giving a bonded textile structure having excellent feeling and heat-resistance can be produced by combining (A) a low-melting copolyester having a crystal melting point of 110-210 deg.C and composed of (i) terephthalic acid as a main acid component and (ii) 1,4- butanediol and 1,9-nonanediol at a molar ratio of 90/10-50/50 as main diol component with (B) a high-melting polymer having a crystal melting point of >=220 deg.C and consisting of preferably polyethylene terephthalte or a polyester composed mainly of the terephthalate. The component A occupies at least a part of the surface of the obtained composite fiber. The composite fiber is preferably a concentric sheath-core composite fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a hot-melt composite binder fiber that has excellent adhesive properties and provides a bonded fiber product with good heat resistance and feel.

(Prior art) In recent years, constituent fibers ( Hot-melt type binder fibers have come to be widely used for the purpose of adhering the main fibers (main fibers) to each other.

The main fiber used is polyester fiber, which is relatively inexpensive and has excellent physical properties.
The binder fiber for bonding this is preferably polyester-based. Various polyester-based binder fibers and polyester fiber structures bonded using the same have been proposed (for example, U.S. Pat. No. 4,129,675 and many others). ).

By the way, what about polyester binder fibers?

Since copolyesters are generally used, they often do not exhibit a clear crystalline melting point (1) and usually soften at 90 to 200°C. Then, the main fibers are bonded together by heat treatment at a temperature higher than the softening point and lower than the melting point of the main fibers.

However, in the case of textile products for industrial materials that are used in high-temperature environments above the glass transition point of the binder fibers, bonding with binder fibers that do not have a clear crystalline melting point will reduce the adhesive strength in the high-temperature atmosphere, causing the product to deteriorate. There was a problem in that the strength of the material decreased and the bulk retention decreased.

In addition, when a composite fiber type binder fiber is made of a copolyester that does not exhibit a crystalline melting point and a high melting point polyester,
After spinning, the fibers fuse when hot drawn, so they must be cold drawn, and with cold drawn binder fibers, there is a problem in that the high melting point polyester shrinks due to heat during use, impairing the appearance of the bonded fiber product.

Hot-melt type binder fibers made of copolyesters exhibiting a crystalline melting point have also been proposed2, for example, JP-A-51
Publication No. 125424 discloses a hot-melt adhesive made of polybutylene terephthalate/polybutylene isophthalate copolyester. For example, when a nonwoven fabric is bonded using this adhesive, the bonded nonwoven fabric becomes paper-like. There was a problem in that the material may be hard to the touch.

Incidentally, JP-A-61-176682 discloses a hot-melt adhesive made of a copolyester of terephthalic acid, 1,4-butanediol and 1,9-nonanediol; Nothing is disclosed about its use.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems of binder fibers and can be produced by a hot stretching method.

It is an object of the present invention to provide a hot-melt type binder fiber that can be effectively bonded without damaging the appearance of the fiber structure, and that provides a bonded fiber structure with a soft texture that exhibits little decrease in adhesive strength even when used in a high-temperature atmosphere. That is.

(Means for solving the problems) The present invention achieves the above objects, and the gist thereof is as follows:
With terephthalic acid as the main acid component, molar ratio 90/10~
A low melting point copolyester with a crystal melting point of 130 to 210 °C and a high melting point of 220 °C or higher with a crystal melting point of 60/40 1,4-butanediol and 2,2-dimethyl-1,3-propanediol as the main diol components. The hot-melt composite binder fiber consists of a polymer and the former occupies at least a portion of the fiber surface.

The low melting point copolyester in the present invention has a clear crystal melting point and a high crystallization rate, and has terephthalic acid as the main acid component and a 2 molar ratio of 90/10 to 50150.
The main diol components are 1,4-butanediol (BD) and 1,9-nonanediol (NO) and have a crystal melting point of 110 to 210°C.

If the crystal melting point is less than 110°C, the adhesive strength will decrease when the bonded fiber product is used in a high-temperature atmosphere, which is undesirable. If it exceeds 210°C, the bonding temperature must be set to a high temperature close to the melting point of the main fiber.

This is undesirable because it impairs the physical properties of the main fiber and the shape of the fiber structure.

Such a copolyester with a crystal melting point of 110 to 210°C is obtained by selecting a molar ratio of a terephthalic acid component and a diol component consisting of BD and ND within the above molar ratio range so as to have a predetermined crystal melting point. It can be obtained by copolymerizing. (If the molar ratio of the diol component is out of the above range, it may not show a clear crystalline melting point, or it may have a high melting point.) In addition, the low melting point copolyester is Other components 9: polycarboxylic acids such as isophthalic acid, trimellitic acid, adipic acid, sebacic acid, diethylene glycol.

It may contain polyols such as triethylene glycol, polyethylene glycol, polypropylene glycol, pentaerythritol, bisphenol A, hydroquinone, etc. as a copolymerization component, and may also contain additives such as flame retardants, stabilizers 1, colorants, etc. You can leave it there.

As the high melting point polymer forming the composite fiber with the low melting point copolyester, polyethylene terephthalate, polybutylene terephthalate, polyester mainly composed of these, nylon 66, etc. can be used, but in particular polyethylene terephthalate and ethylene terephthalate units containing 90
A copolyester containing mol % or more is preferably used from the viewpoint of strength properties.

Note that if the melt viscosity of the low melting point copolyester is too low, the operability during composite spinning will be poor.

By increasing the degree of polymerization, the melt viscosity is 220℃, and the shear rate is 100/
It is desirable to have 200 voices or more in sec.

Composite fibers may be in any form, as long as the low melting point copolyester occupies a small portion (or a portion) of the fiber surface, and may be of concentric or eccentric sheath-core type, or side-by-side type.

It can be made into a composite fiber in which a high melting point polymer is spun in a seabird shape or by inserting a static mixing element into a spinning bag and dispersed in layers or stripes. The concentric sheath-core type has good spinning properties, while the eccentric type has latent crimpability.
It is advisable to select an appropriate composite form depending on the application.

The binder fiber of the present invention can be obtained by subjecting the above-mentioned low-melting point copolyester and high-melting point polymer to composite spinning and drawing in a conventional manner, and cutting the resultant fibers as necessary. Stretching is preferably carried out by a hot stretching method, in which the supply roller is heated or a hot plate is provided between the supply roller and the stretching roller.

This is carried out by heating to 60°C or higher, preferably 80°C or higher.

(Function) Since the binder fiber of the present invention has crystalline copolyester as a thermal adhesive component, once the main fiber is melted and bonded, the copolyester quickly crystallizes when the temperature is lowered, and even if the temperature is raised again, It is recognized that the adhesive strength does not decrease up to a temperature near the melting point of the copolyester and exhibits excellent adhesiveness with excellent heat resistance.

Furthermore, since the low melting point copolyester is combined with the high melting point polymer, the binder fibers do not spread after bonding, so it is recognized that the feel of the bonded fiber structure does not become hard.

(Example) Next, the present invention will be specifically explained with reference to Examples.

Note that the method of measuring the characteristic values in one example is as follows.

■Use a mixture of equal weights of light bark phenol and tetrachloroethane as a solvent at a concentration of 0.5 g/d1. Measured at a temperature of 20°C.

Measured using a differential scanning calorimeter model DC5-2 manufactured by Inomasu Noka PerkinElmer at a heating rate of 20°C/min.

The Oniriki nonwoven fabric was cut into 25 mm width pieces and tested using a constant speed extension type tensile tester.
Measured at a sample length of 100n+ and a tensile speed of 100n/min.

(The strength at 130°C is measured after leaving the sample installation part in a furnace at a predetermined ambient temperature for 90 seconds.) Examples 1 to
4 Dimethyl terephthalate) (DMT) and 1.3 of DMT
0M7 with BD/ND at the molar ratio shown in Table 1 of twice the molar ratio.
Using 3 x 10-' mol of tetrabutyl titanate per 1 mol as a catalyst, polyester exchange polycondensation was carried out in a conventional manner to obtain a copolyester having the relative viscosity and crystal melting point shown in Table 1.

This copolyester has a relative viscosity of 1.3B and a crystal melting point of 25.
Polyethylene terephthalate at 6℃ and 3 using a conventional concentric sheath-core type composite fiber melt spinning equipment.

Using a spinneret with 265 spinning holes, the material was melt-spun at a spinning temperature of 270°C, a discharge rate of about 420 g/min, and a composite ratio of 1:1, so that the former became a sheath, and after cooling, it was taken off at a speed of 1000 m/min. .

The obtained yarn was bundled into a 100,000 d tow and stretched at a drawing temperature of 10
After stretching at 0° C. and crimping with a push-in crimper, the fibers were cut into a length of 51 m to obtain binder fibers with a fineness of 4 d.

This binder fiber and polyethylene terephthalate crimped fiber with a fineness of 2 d and a length of 511 m were mixed at a weight ratio of 40:60, passed through a card to form a web with a basis weight of 40 g/m, and rotated at the temperatures shown in Table 1. A nonwoven fabric was obtained by heat treatment in a dryer for 2 minutes.

The obtained nonwoven fabric has a soft texture.

As shown in Table 1, it had good strength.

Comparative Examples 1-2 The same tests as in Example 1 were conducted except that the BD/NO having the molar ratio shown in Table 1 was used and the stretching was performed at room temperature.

Due to heat treatment, the length and width shrink by more than 15%.

The obtained nonwoven fabric had a slightly hard texture and poor heat-resistant adhesive strength.

Table 1 shows the strength of the nonwoven fabric.

Table 1 Reference Examples A polyethylene terephthalate/polyethylene isophthalate (molar ratio 50,150) copolyester with a relative viscosity of 1.38 and no crystal melting point was used, and the stretching was performed at room temperature and the heat treatment temperature was 150°C. A test similar to Example 1 was conducted.

The obtained nonwoven fabric had a slightly hard texture and a strength of 2.
The weight was 3555g at 5°C and 425g at 130°C.

Example 5 The same test as in Example 3 was conducted using the copolyester of Example 3, except that the form of the composite fiber was changed to a side-by-side type, and the crimp application using a crimper was omitted.

The binder fibers had crimps due to the drawing heat treatment, and the strength of the nonwoven fabric was 1990 g at 25°C and 980 g at 130°C.

(Effects of the Invention) According to the present invention, it is possible to produce hot-melt composite binder fibers with good operability that have excellent adhesive properties and provide bonded fiber structures with good texture and heat resistance. Become.

Claims (4)

[Claims] (1) Terephthalic acid is the main acid component, molar ratio 90
/10-50/50 1,4-butanediol and 1,9
- A hot composite fiber consisting of a low melting point copolyester with a crystalline melting point of 110 to 210°C containing nonanediol as the main diol component and a high melting point polymer with a crystalline melting point of 220°C or higher, the former occupying at least a part of the fiber surface. Melt-type composite binder fiber. (2) The hot melt type composite binder fiber according to claim 1, wherein the high melting point polymer is polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate. (3) The hot melt type composite binder fiber according to claim 1 or 2, wherein the composite fiber is a concentric sheath-core type composite fiber. (4) The hot melt type composite binder fiber according to claim 1 or 2, wherein the composite fiber is an eccentric type composite fiber.