JPH0434018A - Heat bonding conjugate fiber - 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 Field of Application> The present invention relates to a heat-adhesive conjugate fiber that is excellent in spinnability and thermal adhesion, particularly in thermal adhesion. More specifically, the present invention relates to a heat-adhesive conjugate fiber suitable for manufacturing synthetic fiber paper with excellent water resistance and high wet strength.

<Prior Art> In recent years, synthetic paper made by adding chemical fibers such as polyester and vinylon and binders, or natural fibers such as bulbs and linen, has come to be produced. The binder used here is usually highly hydrophilic polyvinyl alcohol fiber, so it collapses into dispersion and provides good adhesion after heat treatment, but it has the disadvantage of having extremely low wet strength due to poor water resistance. there were. As a way to solve this problem, we developed a core-sheath type composite fiber (Japanese Patent Publication No. 54-44
No. 773), and heat-adhesive composite fiber using EVOH as a sheath component and polyester as a core component (Japanese Patent Laid-Open No. 52
-26008 publication, JP-A-57-66200 publication,
JP-A-58-4820, etc.) have been proposed. However, since the former composite fiber uses polypropylene as a core component, it undergoes thermal deformation during the heat bonding process, making it impossible to obtain a bulky nonwoven fabric. Because of the insufficient adhesion, even if it is made into a core-sheath type composite fiber, the fixation of the fibers in the form of intertwining is insufficient, resulting in a disadvantage that a practically sufficient adhesion strength cannot be obtained.

In addition, heat-adhesive fibers made of EVOH alone (Special Publication No. 56
-17442 Publication, Special Publication No. 56-17444)
has also been proposed, but it has disadvantages such as a drop in productivity due to poor spinnability of EVOH, and insufficient adhesive effect as a binder when manufacturing synthetic paper based on polyester fibers. There is.

<Purpose of the Invention> The present invention was made to solve the problems of the above-mentioned prior art, and its purpose is to provide a material that has excellent adhesion to chemical fibers such as vinylon and polyester fibers and has good thread-spinning properties. Another object of the present invention is to provide a heat-adhesive composite fiber suitable for manufacturing synthetic fiber paper.

<Structure of the Invention> As a result of intensive studies to achieve the above object, the inventors of the present invention surprisingly found that when a low melting point polyester is added to EVOH as a thermal adhesive component, the adhesiveness with polyester fibers is improved. The present invention was achieved based on the discovery that not only the properties but also the wet strength were improved.

That is, according to the present invention, there is provided a composite fiber composed of component A and component B containing the following polymers, wherein component A is continuously exposed on the fiber surface in the fiber axis direction and has a surface area ratio of Component A of thermoadhesive conjugate fiber characterized by a content of 40% or more (1) Ethylene vinyl alcohol copolymer having 30 to 70 mol% of ethylene units and 70 to 30 mol% of vinyl alcohol units: 99 to 70% by weight %0) Low melting point polyester (1) with a melting point of 80-180°C
21 to 30% by weight of component B (up to) A polyester (n) whose main repeating unit is alkylene terephthalate and whose melting point is 200°C or higher is provided.

The ethylene vinyl alcohol copolymer (EVOH) used as component A constituting the composite fiber of the present invention has a copolymerization ratio of ethylene units of 30 to 70 mol% and a copolymerization ratio of vinyl alcohol units of 70 to 30 mol%. There needs to be. If the copolymerization ratio of ethylene units is less than 30 mol%, not only will the melt spinnability of EVOH decrease, but also the melting point will decrease to 1.
Since the temperature is 80° C. or higher, the thermal adhesion treatment temperature must also be high, which is not preferable because the adhesion treatment in a dryer in the papermaking process becomes difficult. On the other hand, if it exceeds 70 mol %, the EV OH becomes too hydrophobic and the thermal adhesion properties decrease, resulting in a decrease in the strength of the resulting paper, and in extreme cases, it becomes impossible to form a paper layer.

Furthermore, during papermaking, the transfer of the paper from the paper screen to the felt section is insufficient, and the melting point of EVOH is also lowered, resulting in stickiness to the dryer surface, causing surface stains.

Such an ethylene vinyl alcohol copolymer is usually produced by saponifying the acetate group of an ethylene vinyl acetate copolymer, but it is desirable to use a saponification degree of 98% or more. If the degree of oxidation is less than 98%, it is undesirable because it may thermally decompose during melt spinning and generate acetic acid, resulting in poor spinning performance.

If the melting point (softening start temperature for amorphous polyester) of the low melting point polyester (I) used as component A constituting the composite fiber of the present invention is too high, the thermal adhesiveness will decrease and the paper obtained will be The strength of
-180°C, preferably 120-180°C.

The low melting point polyester (I) is not particularly limited as long as it satisfies the above melting point, and may be a conventionally known acid component or glycol component.

Among such polyesters, the acid components include terephthalic acid, isophthalic acid, and phthalic acid.

Adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, etc., and glycol components such as ethylene glycol, propylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol,
Copolyesters using 1,4-cyclohexane dimetatool, polyoxyalkylene glycol, etc. are inexpensive and preferred.

In the present invention, the contents of the BVOH and the low melting point polyester CI) are 99 to 70% by weight and 1 to 30% by weight, respectively, based on component A. When the amount is within this range, not only the adhesiveness is improved but also the water resistance of the resulting paper is significantly improved, although the detailed reason is unknown. On the other hand, if the blending amount is outside the above range, sufficient adhesive strength or water resistance may not be obtained, which is not preferable.

Component B constituting the composite fiber of the present invention is preferably a polyester (II) whose main repeating unit is alkylene terephthalate and has a melting point of 200°C or higher from the viewpoint of shape retention, water resistance, and II mechanical properties. , i! ! 200 points
If the temperature is less than 0.degree. C., thermal deformation may occur during thermal bonding, which may change the form of the paper, which is not preferable.

Examples of such polyesters (If) include polyethylene terephthalate and copolymerized polyesters obtained by copolymerizing polyethylene terephthalate with 10 mol % or less of a third component. Further, as the third component, any compound commonly used in polyester production can be used, such as 5-sodium sulfoisophthalic acid, isophthalic acid, adipic acid, sebacic acid, diethylene glycol, triethylene glycol, and polyethylene glycol.

In addition, in the present invention, 1 to 30% of EVOH is added to the B component.
It is a more desirable embodiment to blend the resin in an amount of 1 to 10% by weight, especially since the adhesiveness is improved.

Next, the composite type of the composite fiber of the present invention does not need to be particularly limited as long as the A component is continuously exposed on the fiber surface in the fiber axis direction and the surface area ratio occupied by it is 40% or more.
(Eccentric) It can be either a core-sheath type or a side-by-side type, or it can be a multi-layer parallel type or a multi-core type. Among these, the core-sheath type composite fiber improves the strength of the final paper. This is a desirable form. If the ratio of the surface area occupied by component A to the total surface area of the fibers is less than 40%, it is not preferable because sufficient adhesive strength cannot be obtained.

There is no need to specifically limit the composite ratio of component A and component B, but if the amount of component A is too small, the adhesiveness will decrease, and if it is too large, the mechanical properties will be insufficient. /
B (weight ratio) is 8/2 to 2/8, preferably 4/6 to 6
/4 is desirable.

In addition, commonly used additives such as dyes, pigments, matting agents, antifouling agents, antioxidants, ultraviolet absorbers, antistatic agents, and flame release agents may be added to component A and/or component B. .

The heat-adhesive composite fiber of the present invention described above can be produced extremely stably using commonly known composite spinning equipment. For example, low melting point polyester (I) and EVOH are melt-mixed at 170 to 230°C, while polyester (n
) are melted at 270-300℃, and these are melted at 280-300℃.
Composite spinning is performed by extrusion from a composite spinneret set at 0°C. Next, to obtain long fibers, the fibers are stretched 3 to 5 times using a heating roller or heating pin at 60 to 80°C. When obtaining short fibers, they are drawn 2 to 4.5 times in a hot water bath at 70 to 80°C. If necessary, the stretching may be followed by heat treatment under relaxation or tension, or crimping may be applied.

<Effects of the Invention> The heat-adhesive composite fiber of the present invention described above contains a heat-adhesive component (component A), EVOH and low melting point polyester CI).
Because it is made of a mixture of .

(2) Although the detailed reason is unknown, the presence of low melting point polyester improves the water resistance of lick F and VOH.
It is estimated that some of the hydroxyl groups of H have reacted with the low melting point polyester (I), and the wet strength of the resulting nonwoven fabric is improved.

It has the following characteristics. Furthermore, since component A contains low melting point polyester (I), +3) interfacial peeling within the composite fiber is suppressed and adhesion is improved.

It also has the following characteristics.

Moreover, since the polyester (1) with good spinnability is composite-spun, even though EVOH, which normally has poor spinnability when used alone, is used, it is possible to produce yarn extremely stably.

When the heat-adhesive fiber of the present invention is used as short fiber, natural fibers such as bulbs and hemp can be used. Synthetic fiber paper can be made by wet paper making with or without mixing fibers of the same color as fibers or chemical fibers such as polyester and vinylon, followed by wet heat bonding treatment.

The resulting paper not only has high paper strength and wet strength;
Since it also has heat-sealing properties, it is suitable for tea bag paper, teak scouring paper, confectionery wrapping paper, bulky tissue vapor, etc., and can also be used as a base paper for adhesive tapes.

On the other hand, in the case of long fibers, they can be used as ropes for large seaweed cultivation nets with strong water resistance, or for various rubber-based fabrics by taking advantage of their good adhesion processability with rubber.

<Examples> Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Ethylene vinyl alcohol copolymer (ethylene/vinyl acid #45155 molar ratio copolymer with a degree of genification of 99.8 mol%, melt flow rate -5.5: EVOH1) as a sheath component (component A) ) and low melting point polyester (■
) (Terephthalic acid: Isophthalic acid #!i: Sebacic acid-6
:2:2 (mole ratio), '1.4-butanediol, melting point 150°C: Polyester 1) was mixed in the ratio shown in Table 1, while the core component (B component) was the above EVOH. and polyethylene terephthalate having an intrinsic viscosity of 0.64 in the proportions listed in Table 1 were used to spin core-sheath type composite fibers with a composite ratio of 50/50. On this occasion,
The core component was melted at 280°C, and the sheath component was melted at 230°C, supplied to a composite spinneret, extruded from a nozzle under 290°C, and wound up at a speed of 1150 m/min to 2680 de/45
An undrawn yarn of 0f i I was obtained. This undrawn yarn is 230
The yarns were combined, stretched 1.9 times in a 70° C. hot water bath, then 1.05 times stretched in an 80° C. hot water bath, and then dried at room temperature under relaxation. The obtained fiber had a denier of about 3.0 and had the single yarn physical properties listed in Table 1.

This composite fiber was cut into lengths of 5t1m and 3 (hu
t%, single yarn denier 1 denier fiber length 5-4 polyester fibers (hvt% and 30 wt% of wood pulp beaten to 500 m1 of P water rings were dispersed in water at a fiber concentration of o, 3 wt%, and a cylinder test paper was made. Paper making using a machine, then 120
Dry in a drum dryer set at °C. The properties of the obtained mixed paper are also shown in Table 1.

As is clear from the results, the paper using the composite fiber of the present invention had good paper strength and good wet stability.

Example 2 Polyethylene terephthalate with an intrinsic viscosity of 0.64 was used as the core component (component B), and as the sheath component, EVOH and low melting point polyester having an ethylene/vinyl alcohol copolymerization ratio listed in Table 2 were used at 9/1 ( A composite ratio of 51 was prepared in the same manner as in Example 1 except that the mixture was mixed at a ratio of
A core-sheath type composite fiber (3.0 denier) of No. 5 was obtained.

50 wt % of the obtained composite fibers and vinylon fibers having a single yarn denier of 1.5 denier and a fiber length of 5 IuI were mixed and processed in the same manner as in Example 1 to obtain a synthetic paper. These performances are shown in Table 2.

Example 3 Polybutylene terephthalate containing 10% by weight of EVOH (intrinsic viscosity 1.06) as a core component (component B), a sheath component (
EVOHl containing 10% by weight of polyester 3 as component A) was melted at 280°C and 230°C, respectively, extruded from a composite spinneret heated to 290°C, and wound up at a spinning speed of 1150 m/min. At this time, the core-sheath composite ratio was 50:50, and the obtained undrawn yarn was 2680 denier/450 filament.

This undrawn yarn was drawn in two stages in a hot water bath in the same manner as in Example 1 to obtain a composite fiber having a single yarn denier of 3.0 denier, a strength of 5.2+r/denier, and an elongation of 43%.

This composite fiber (cut length 5 cm > 30 wt%,
When mixed with 70 wt% of the same wood pulp used in Example 1, the basis weight was 32 tlrd and the thickness was 0.088 cm.
, a paper with a density of 0.38 g/, 3 was obtained. The dry strength of this paper is vertical.

The wet strength is 1.5 kg/15+m+, 0 for horizontal 2.6 hz/15 yen and 1.0 dazzle/15 yen, respectively.
．． It was excellent at 6 kg/15 am.

On the other hand, a composite fiber obtained in the same manner without using polyester 3 as a sheath component has a strength of 3.5 f/de + elongation of 4
8%, and the dry strength of the paper obtained in the same manner as above using this was 1 and 8 g/15m047kg in the vertical and horizontal directions, respectively.
/15 darkness, wet strength is 0.5wg/15m+ respectively
, it was as low as 0.2m/15 cities.

Example 4 A mixture of EVOHl and low melting point polyester (■) (polyester 1) in a ratio of 9/1 was used as the sheath component (component A), while as a core component (component B), a mixture with an intrinsic viscosity of 0
．． Composite ratio 5 using polyethylene terephthalate of 64
A core/sheath type composite fiber having a ratio of 0:50 was obtained under the same spinning and drawing conditions as in Example 1. The obtained fiber (single yarn denier 3.0 denier, strength 3.0°/denier, elongation 38%) was
30wt% of the cut material is mixed with 70wt% of polyester fiber with a single yarn denier of 0.5 denier and a fiber length of 5mm, and the basis weight is 34g/rrr, the thickness is 0.120cm, and the density is 0.28g/cI? got the paper.

The dry strength of this paper is 2.2 +r/1 in both the vertical and horizontal directions.
5om.

For 0,91qr/1511fI, the wet strength is 1.4kg/15air and 0.5kg/1, respectively.
It was excellent at 5ouo. On the other hand, a composite fiber obtained in the same manner without using the low melting point polyester (Polyester 1) in the sheath component had a strength of 2.9 g/denier,
The elongation is 36%, and the dry strength of the paper obtained in the same manner as above is vertical.

Each side 1.5 m/15IuI, 0.8kg/
15om, wet strength is vertical and horizontal respectively o, si+g,
/ 15am, it was as low as 0.3kg/15 yen.

Claims (3)

[Claims] (1) A composite fiber composed of A component and B component containing the following polymers, in which the A component is continuously exposed on the fiber surface in the fiber axis direction and has a surface area ratio of 4.
A thermoadhesive composite fiber characterized by having a content of 0% or more. Component A (I) Ethylene vinyl alcohol copolymer having 30 to 70 mol% of ethylene units and 70 to 30 mol% of vinyl alcohol units: 99 to 70% by weight (II) Low melting point polyester with a melting point of 80 to 180°C: 1
~30% by weight Component B (III) Polyester (II) whose main repeating unit is alkylene terephthalate and whose melting point is 200°C or higher (2) The thermal adhesive according to claim (1), wherein component B contains 1 to 30% by weight of an ethylene vinyl alcohol copolymer having 30 to 70 mol% of ethylene units and 70 to 30 mol% of vinyl alcohol units. Composite fiber. (3) The thermoadhesive composite fiber according to claim (1) or (2), wherein the composite fiber is a core-sheath type composite fiber.