JPH02191712A - Binder fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber giving a nonwoven fabric having excellent adhesive properties to an aromatic polyester fiber, exhibiting sufficient adhesion strength by heat treatment at low temperature for short time and having excellent maintenance of bulkiness containing a specific copolyester as an adhesive component. CONSTITUTION:At least a part of the surface of the aimed fiber is a copolyester having >=0.6 intrinsic viscosity [eta] composed of (A) terephthalic acid as acid component and (B) 60-40mol% pentamethylene glycol and 40-60mol% tetramethylene glycol as a glycol component. Said fiber is preferably a core- sheath type conjugate fiber containing the above-mentioned copolyester as the sheath component and polyethylene terephthalate, etc., as the core component.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to binder fibers. More specifically, it is suitable for adhesion between polyester fibers, and sufficient adhesive strength can be obtained by heat treatment at a relatively low temperature and in an extremely short time, and furthermore,
The present invention relates to binder fibers suitable for producing nonwoven fabrics with excellent bulk retention properties.

<Prior art> Binder fibers for producing nonwoven fabrics by heat-sealing fibers have been known for a long time, such as core-sheath composite fibers with polypropylene and polyethylene as an adhesive component, and ethylene-vinyl alcohol copolymers. There are composite fibers with polyethylene terephthalate (hereinafter sometimes referred to as PET) that has PET as an adhesive component. In recent years, the role of polyester fibers such as PET has grown in the textile field, especially in the nonwoven fabric field, and from the viewpoint of production efficiency, energy saving, pollution prevention, etc., there is a demand for producing fiber aggregates or textile products, especially nonwoven fabrics, by thermal bonding. As a result, binder fibers for polyester are highly desired.

The above binder fibers have good thermal adhesion between adhesive components, but when used in combination with other main fibers such as for non-woven fabrics, the types of main fibers that can be bonded are very limited. However, no material capable of adhering to polyester fibers has been obtained. For example, although polyethylene is self-adhesive, it hardly adheres to common commercially available fibers with different chemical structures. In addition, copolymerized nylon is nylon ll
Although it adheres to other materials, it does not adhere to polyester fibers made of the same condensed polymer. Additionally, ethylene-vinyl alcohol copolymers exhibit adhesion to rayon, vinylon, or nylon, which have relatively similar solubility parameters, but they also do not adhere to polyester.

In order to bond polyester fibers, it is common sense to use a polyester polymer as an adhesive component due to the similarity in chemical structure and solubility parameters. In fact, many copolymerized polyesters have been proposed as solvent-soluble or hot-melt adhesives that use polyester as an adhesion partner.

However, in the production of nonwoven fabrics, etc., production efficiency and
From the viewpoint of energy saving, etc., a method of thermal bonding using heat treatment at a relatively low temperature of approximately 100 to 150°C and in an extremely short time (10 seconds or less) is generally adopted. When using a copolymerized polyester based on a copolymerized polyester as an adhesive component, the amount of the copolymerized component (e.g., isophthalic acid, diethylene glycol, etc.) is greatly reduced to significantly lower the softening start temperature. There is a need. However, in this case, the crystallinity of the copolyester decreases significantly and the crystallization rate slows down, so when the fiber bundle after spinning is placed in a can or wound up on a bobbin, it is difficult to use single fibers, strips, or fibers. Severe adhesion between the bundles makes it difficult to obtain spun fibers. Further, even if the fibers can be cured, there are problems such as insufficient adhesion after short-term heat treatment or frequent adhesion problems during adhesion processing.

In order to lower the melting point while maintaining the crystallinity of polyester, a method of using aliphatic dicarboxylic acid instead of terephthalic acid and ethylene glycol.

There is a method in which a longer chain alkylene glycol is used instead of butylene glycol. However, in the former method, there are problems such as (because of the low thermal stability of the polyester to be hydrogenated, it is easily thermally decomposed during melt-spinning, and its adhesive strength to fibers made of aromatic polyester such as PET is low. .

On the other hand, in the latter method, the melting point of polyester is adjusted to the heat treatment temperature (usually 100 to 150
℃), it is necessary to use an alkylene glycol having 5 or more carbon atoms.

However, the melting point of polyester obtained from heptamethylene glycol and nonamethylene glycol is 95, respectively.
℃, 92°C, which is less than 100°C, which is too low to be used practically. Furthermore, alkylene glycol having a longer chain than octamethylene glycol is extremely expensive or difficult to obtain, and therefore is not suitable for industrial scale production. Furthermore, alkylene glycols with longer chains than heptamethylene glycol have very high boiling points and low polycondensation reactivity, so they are not suitable for industrial scale production. On the other hand, pentamethylene glycol or heptamethylene glycol is relatively inexpensive, and the melting points of the polyester obtained are 134°C and 146°C, respectively, which are considered suitable as adhesive components for binder fibers.

Binder If containing such polyester as an adhesive component
As such, a method using polyhexamethylene terephthalate or a copolyester obtained by partially copolymerizing isophthalic acid with it has already been proposed (for example, in Japanese Patent Application Laid-Open No. Sho 52).
-96235, JP-A-57-133217, etc.). However, although these polyesters exhibited fairly good adhesion to polyester fibers, they had the following drawbacks.

That is, (1) nonwoven fabrics obtained using these binder fibers have a soft texture, but on the other hand, they have poor bulk retention properties, and therefore, when stored under load, the bulk decreases and the commercial value decreases. ■Hexamethylene glycol is solid at room temperature, making it difficult to handle on an industrial scale. ■Hexamethylene glycol has an extremely high boiling point of about 250°C, so the polycondensation reaction rate is slow. (2) Since the glass transition point of polyester is extremely low at approximately -10°C, it is often difficult to pelletize it using conventional polyester production equipment.

As described above, the reality is that a fully satisfactory binder If suitable for adhering polyester fibers has not yet been obtained.

<Objective of the Invention> The object of the present invention is to provide excellent adhesive strength to aromatic polyester fibers such as PET, especially at low temperatures (100 to
The purpose of the present invention is to provide a binder fiber that can be bonded by short-time heat treatment at 150°C), is suitable for producing nonwoven fabrics, and has a non-mr of 15 with excellent bulk retention.

<Structure of the Invention> As a result of studies to achieve the above object, the inventors have discovered that
It has been found that a nonwoven fabric obtained using binder fibers containing pentamethylene terephthalate as an adhesive component has excellent bulk retention.

However, since this polyester has an extremely slow crystallization speed compared to PET, PBT, etc., the pellets stick together during the pelletizing process after producing the polyester.

I also learned that there is a problem with industrial production due to the severe sticking of fibers during spinning.

The inventors of the present invention have made further intensive studies to improve these drawbacks, and have surprisingly found that by using a mixture of pentamethylene glycol and tetramethylene glycol in a specific range as glycol components, the above drawbacks can be overcome. It was discovered that the bulk retention of the resulting nonwoven 15 could be maintained, and the present invention was achieved.

However, in the present invention, the main acid component is terephthalic acid, and the main glycol components are 60 to 40 mol% of pentamethylene glycol and 4% of tetramethylene glycol.
A binder fiber containing a copolymerized polyester having an intrinsic viscosity of 0 to 60 mol% and having an intrinsic viscosity of [410.6 or more] as an adhesive component must necessarily have the copolymerized polyester constituting at least a part of the fiber surface. This is a characteristic binder fiber.

In the binder fiber of the present invention, the acid component constituting the copolymerized polyester serving as the adhesive component mainly consists of a terephthalic acid component. Here, mainly means 8 of the acid component.
This means that 0 mol% is the terephthalic acid component, and a small amount of other acid components such as isophthalic acid, adipic acid, etc.
Copolymerization may be carried out at a ratio of mol% or less. However, since the desired low melting point, highly crystalline polyester can usually be obtained using the terephthalic acid component alone, it is preferable not to use other acid components.

On the other hand, as for the glycol component, it is necessary that 40 to 60 mol% be a pentamethylene glycol component and 60 to 40 mol% be a tetramethylene glycol component. If the pentamethylene glycol component is less than 40 mol%, the final bulk retention of the nonwoven fabric (7) will be insufficient, and a product with little settling will not be produced.On the contrary, if the pentamethylene glycol component is less than 60 mol% If it exceeds mol%,
As mentioned above, pellets and fibers often stick together, making it unsuitable for production.

Furthermore, it is important to use tetramethylene glycol as a glycol component used in combination with pentamethylene glycol. Even if other glycol components such as ethylene glycol, trimethylene glycol, hexamethylene glycol, etc. are used, the effect of increasing the crystallization rate of the copolyester and reducing the sticking of pellets and fibers as in the present invention cannot be obtained. I can't. Although a small amount (20 mol % or less of the glycol component) of other glycol components other than pentamethylene glycol and tetramethylene glycol may be copolymerized as the glycol component, it is usually preferable not to copolymerize.

Such a copolyester can be produced by a conventionally known method. For example, the dicarboxylic acid component and the glycol component are subjected to an engineering or transesterification reaction in the presence or absence of a catalyst to produce a bisglycol ester and/or
or obtain an initial condensate thereof. It can then be easily obtained by carrying out a polycondensation reaction in the presence of a polycondensation catalyst. On this occasion,
When a titanium compound, especially a reaction product of a tetraalkyl titanate and an organic carboxylic acid and/or its acid anhydride is used as a polycondensation catalyst, the polycondensation reaction rate becomes faster and a polyester with a high degree of polymerization can be easily obtained. preferable.

The tetraalkyl titanates used in the production of such reactive products are preferably those having an alkyl group having 3 to 4 carbon atoms, particularly tetrapropyl titanate, tetraisopropyl titanate, and tetrabutyl titanate, and organic carboxylic acids and/or Examples of the acid anhydrides include aliphatic carboxylic acids such as acetic acid and propionic acid, aromatic polyvalent carboxylic acids such as phthalic acid, trimellitic acid, hemimellitic acid, and pyromellitic acid, and acid anhydrides of these acids. be able to. There is no need to specifically limit the conditions for reacting these, and for example, the components can be easily obtained by dissolving each component in a solvent such as ethylene glycol and reacting at about 80° C. for about 60 minutes.

There is no need to particularly limit the amount of the polycondensation catalyst used, but if it is too small, the polycondensation reaction rate will be slow, while if it is too large, the hue of the resulting polyester tends to deteriorate (yellowing).

Therefore, although it varies depending on the type of catalyst used,
In the case of the reaction product, the titanium atom in the reaction product is 0.005 to 0 with respect to the acid component of the copolymerized polyester.
．． An amount of 1 mol %, especially 0.01 to 0.05 mol % is preferred.

Further, when the reaction product is used as a polycondensation catalyst, it is preferable to use a sulfonic acid compound represented by the following general formula (I) as a hue improver.

A-3O3M...(I) However, A is an alkyl group of C, and M is 1-1. Al 1-20 Potash metal or alkaline earth metal, especially
K, Na, and 1/'2 Ca are preferred, and two or more of these may be used in combination.

The sulfonic acid compound is preferably used in an amount ranging from 1740 to 20 times, particularly 1/20 to 5 times, by mole, relative to the mole of titanium atoms in the reaction product. If the amount is less than /40 times by mole, coloring of the polyester cannot be suppressed and the thermal stability becomes low. On the other hand, if the amount exceeds 20 moles, the effect of preventing coloration not only becomes saturated, but also causes a remarkable foaming phenomenon during the polycondensation reaction, and at the same time causes an increase in pack pressure and yarn breakage during the spinning process, as well as yarn breakage during the drawing process. This is not desirable because it tends to cause frequent problems.

Note that the polycondensation catalyst and the hue improver may be added at any time as long as they are before the start of the polycondensation reaction, and both may be added separately or at the same time.

Further, as for the hue improver, it is possible to delay the addition time even after the polycondensation reaction has started but before the reaction is completed.

Intrinsic viscosity of the copolymerized polyester thus obtained [η]
(measured at 30°C in orthochlorophenol solvent) is 0
．． 6 or more, preferably 0.7 or more 1, particularly preferably 0
．． Must be 8 or higher. If the intrinsic viscosity is less than 0.6, the mechanical properties of the copolyester will deteriorate and the strength of the nonwoven fabric obtained in the final curve will be insufficient, which is not preferable.

The copolymerized polyester used in the present invention may contain small amounts of additives such as matting agents, antioxidants, optical brighteners, stabilizers, and ultraviolet absorbers.

The binder fiber of the present invention may be a fiber spun alone from the above-mentioned copolymerized polyester, but it is more preferably a composite m-fiber spun together with another melt-spun polymer.

Such polymers are fiber-forming and have a melting point of 180°C.
The above thermoplastic polymers are used, such as PET,
PBT, nylon-6, nylon 6.6, etc. are preferably used. In addition, the copolymerized polyester serving as an adhesive component accounts for at least a portion, preferably 40%, of the surface of the composite fiber.
must account for more than that. If the copolymerized polyester is not exposed on the surface of the composite fiber, it is not preferable because a sufficient adhesion effect cannot be obtained.In addition, in any cross section of the composite fiber, the area ratio of the copolymerized polyester is preferably 10% to 70%, more preferably 30% to 70%, particularly preferably 25% to 50%.

Such composite fibers may take any form such as side-by-side type composite fibers or core-sheath type composite fibers.
Particularly preferred are core-sheath type composite fibers containing string-forming polyester as a core component.

The binder fiber of the present invention can also be used as an adhesive fiber aggregate consisting only of the binder fiber.
Mixed adhesion with other fibers containing the above I! It may also be used as a cloth collection.

Effects of the Invention> The binder fiber of the present invention has excellent productivity and is particularly suitable for producing nonwoven fabrics. In other words, it is possible to easily create a nonwoven fabric with high strength, bulk retention, and slipperiness. Especially, even when using 41 fibers made of PET and PBT as the main fibers, adhesion at m distances is good. A nonwoven fabric with high strength and excellent bulk retention properties can be obtained.

In addition, by using a specific polycondensation catalyst and a hue improver together when producing copolymerized polyester, binder fibers with even higher whiteness and higher commercial value can be easily obtained.
The significance of the invention is extremely canine.

<Examples> Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Note that parts in the examples indicate parts by weight. In addition, various properties were evaluated by the following methods.

(1) Intrinsic viscosity [η1 Measured at 30°C using orthochlorophenol as a solvent,
It was determined from the relative viscosity using a conventional method.

(2) Hue L value and b value are values measured using a Hunter type color difference meter, and the higher the L value, the higher the whiteness, and the lower the b value, the lower the yellowness. That is, it shows that the hue is good.

(3) Thermal stability △IV The copolymerized polyester was melted and held at 260'C for 30 minutes under a nitrogen stream, and the decrease in intrinsic viscosity at that time was measured. △
The smaller Iv is, the better the thermal stability of the copolyester is.

(4) Adhesive strength The obtained binder fiber (6 denier
Create a sliver by blending at a ratio of 0:80,
The handling strength was measured. On the other hand, a sliver prepared in the same manner was heat treated at 160° C. for 30 seconds under a load of 5 (1/Cl112) to measure its handling strength, and the adhesive strength was determined using the following formula.

Strong adhesive strength after pulling after heat treatment = (5) Bulky retention and strong handling before heat treatment Obtained binder, fiber 1 (6 denier x 51F + ll
PET stable fibers (6 denier x 51 mm) having the same crimp ratio of <10% as in 1) were blended in the card (weight ratio 20:80) [, 15 per card].
A 1 q web having a basis weight of 0 g was heated for 5 minutes in a hot air oven adjusted to 160°C. The web thus obtained was cut into squares of 20 cm on each side, stacked so that the total weight was about 80 g, a plate weighing 5000 q was placed on top, and left for 24 hours, the load was removed, and after 5 minutes had elapsed. The height was measured and calculated from the following formula.

Wear height and bulk retention after applying load - Web height before applying load Example 1 (a) Preparation of titanium catalyst (CAT) 2.5 parts of ethylene glycol and 0.5 parts of trimellitic anhydride were added.
After dissolving 8 parts of tetrabutyl titanate, 0.7 parts of tetrabutyl titanate (
(172 mol relative to trimellitic anhydride) was added dropwise to the mixture, and the mixture was kept at 80° C. under normal pressure in air to react for 60 minutes. Thereafter, the mixture was cooled to room temperature, 15 parts of acetone was added to precipitate the reaction product, and the mixture was dried separately at 100° C. for 2 hours. The titanium content in the reaction product obtained was 11.5% by weight.

(b) Synthesis of polyester 970 parts of dimethyl terephthalate, 302 parts of pentamethylene glycol, 279 parts of tetramethylene glycol, and 1.23 parts of manganese acetate using a transesterification catalyst were added to a stirrer, a rectification column, and a methanol distillation condenser. The mixture was charged into a reactor provided and heated while gradually increasing the temperature from 130° C. to 180° C., and methanol produced as a result of the reaction was distilled out of the system to perform a transesterification reaction. Three hours after the start of the reaction, the internal temperature reached 180°C, and 320 parts of methanol was distilled out.

After adding 0.77 parts of trimethyl phosphate as a stabilizer and further adding 0.57 parts of the precipitate obtained in (a) above as a polycondensation catalyst, 0.31 parts of sodium alkyl sulfone having an average carbon number of 14 was added. was added. This reaction mixture was transferred to a reactor equipped with a stirrer and a glycol distillation condenser, and the temperature was gradually raised from 180° C. to 240° C., while the pressure was lowered from normal pressure to a high vacuum of 1 mmHg to carry out a polycondensation reaction. In the total polycondensation reaction time of 3 hours, [η
]0.818 of the polymer was obtained.

The hue of this polymer is L value 76.2. The b value was 1.5, the melting point was 129°C, and the thermal stability ΔIV was 0.023.

(c) Production of binder fibers The obtained copolymerized polyester was dried at 70°C in a vacuum dryer, extruded at a die hole diameter of 0.3 mm, number of holes 250, and a die temperature of 220°C, and drawn off at a rate of 800 m/min.

This yarn was stretched 3.5 times in a water bath at 78°C, then shrunk by 10% in a water bath at 87°C, and further crimped with a crimp rate of 10% using a push-in crimper. The obtained crimped yarn was cut into lengths of 60111 mm and 51 mm to obtain binder fibers having a single yarn denier of 6 deniers. The adhesive strength of this product is 36. The bulk retention was 78.

Examples 2 and 3, Comparative Examples 1 and 2 Same as Example 1 except that dimethyl terephthalate, pentamethylene glycol, hexamethylene glycol, polycondensation catalyst and alkyl sulfonic acid compound were changed as shown in Table 1. Copolymerized polyester and binder fibers were obtained. The results are also shown in Table-1.

Examples 4 and 5, Comparative Example 3 921.5 parts of dimethyl terephthalate, 43 parts of adipic acid.
By using the same polycondensation catalyst and hue improver as in Example 1 except for using 5 parts of pentamethylene glycol, 239 parts of pentamethylene glycol, and 333 parts of tetramethylene glycol, and by changing the small condensation reaction time, the intrinsic viscosity shown in Table 1 was obtained. Copolymerized polyesters with different values were obtained.

These were made into binder fibers in the same manner as in Example 1. The results are also shown in Table-1.

Comparative Examples 4 and 5 Copolymerized polyester and binder fibers were obtained in the same manner as in Example 1, except that instead of the combination of pentamethylene glycol and tetramethylene glycol, the glycol components listed in Table 1 were used in combination. .

The results are shown in Table-1.

Examples 6 to 10 Copolymerized polyesters were obtained in the same manner as in Example 1, except that the polycondensation catalyst and hue improver were changed as shown in Table 1, and the polycondensation time was changed.

The obtained polyester was used as a sheath, and the intrinsic viscosity [η] was 0.
64 PET as a core, the spindle hole diameter was 0.35 mm, the number of holes was 2502, the metal temperature was 285° C., and the composite fiber was discharged at a core/sheath ratio of 50,150 to obtain a composite fiber, which was drawn off at a speed of 800 m/min. This yarn was drawn 3.8 times in a water bath at 80°C, then shrunk by 10% at 90°C in a water bath, and further crimped with a crimp ratio of 10% using a force crimper. The 1-year-old crimped yarn was cut into 51 mm and 60 mm pieces to obtain core-sheath type composite binder fibers with a single yarn denier of 6 deniers.

The results are also shown in Table-1.

Claims (2)

[Claims] (1) The main acid component is terephthalic acid, and the main glycol components are 60 to 40 mol% of pentamethylene glycol and 40 to 60 mol% of tetramethylene glycol.
A binder fiber comprising a copolymerized polyester having an intrinsic viscosity [η] of 0.6 or more as an adhesive component, characterized in that the copolymerized polyester constitutes at least a part of the fiber surface. fiber. (2) The copolymerized polyester uses a reaction product of a tetraalkyl titanate and an organic carboxylic acid and/or its acid anhydride as a polycondensation catalyst, and 1/40 to 20 mol based on the titanium atom in the catalyst. The binder fiber according to claim 1, which is a copolymerized polyester in which a sulfonic acid metal salt represented by the following general formula (I) is used as a hue improver during polycondensation. A-SO_3M...(I) [However, A is an alkyl group of C_1_-_2_0, M is H
, alkali metal, or alkaline earth metal]