JPS63182414A - Binder fiber - Google Patents

Abstract

PURPOSE:To provide the titled fiber capable of bonding at low temperatures in a short time for use in the production of nonwoven fabrics, with its surface constituted of a polyester prepared from terephthalic acid (and isophthalic acid) and tetramethylene glycol using each specific polycondensation catalyst and tint improver. CONSTITUTION:First, a polyester is prepared by polycondensation, using as the catalyst, a reaction product from a tetralkyl titanate and organic carboxylic acid (anhydride) and as the tint improver in this polycondensation, 1/40-10 molar times per mole of titanium atom, of a sulfonic acid metal salt of formula [A is 1-20C alkyl; M is H or alkali (alkaline earth) metal] between (A) as the acid component, (i) 40-100mol.% of terephthalic acid and (ii) 60-0mol.% of isophthalic acid and (B) as the glycol component, (iii) tetramethylene glycol or (iv) hexamethylene glycol. Thence, a melt spinning is carried out so that the above polyester constitute at least part of the resulting fiber surface, thus obtaining the objective fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to binder fibers, and more particularly to binder fibers that exhibit sufficient adhesive strength to polyester fibers and the like by heat treatment at a relatively low temperature and in an extremely short period of time.

(Prior art) As a heat-adhesive composite binder fiber for producing nonwoven fabrics, etc., for example, a heat-adhesive composite binder fiber (hereinafter referred to as binder) whose adhesive component is polyethylene, copolymerized nylon, or ethylene/vinyl alcohol copolymer is used. fibers) are used.

By the way, in recent years, polyester fibers such as polyethylene terephthalate (hereinafter sometimes referred to as PET') have been playing an increasingly important role in the textile field, especially in the nonwoven fabric field, and binder fibers are becoming more and more important from the viewpoint of production efficiency and energy saving. There has been a growing demand for the production of fiber aggregates or textile products, especially non-woven fabrics, using polyester as a binder fiber for general use. However, conventionally used binder fibers have good thermal adhesion properties between adhesive components, but when used in combination with the main fiber used in nonwoven fabrics, the type of main fiber that can be bonded For example, binder fibers containing polyethylene as an adhesive component have self-adhesive properties, but general commercially available fibers with a different chemical structure have In addition, binder fibers containing copolymerized nylon as an adhesive component adhere to nylon fibers but not polyester fibers, and binder fibers containing ethylene/vinyl alcohol copolymer as an adhesive component: Rayon and vinylon have relatively similar solubility parameters.

Alternatively, it shows adhesion to nylon, but it also does not adhere to polyester fibers.

Therefore, for bonding polyester fibers, binder fibers whose adhesive component is a polyester polymer having similar chemical structures and solubility parameters are suitable.

However, in the production of nonwoven fabrics, etc., production efficiency and
From the viewpoint of energy saving, etc., a method of bonding by heat treatment at a relatively low temperature of about 100 to 150 degrees Celsius and for an extremely short time (10 seconds or less) is generally used. Therefore, the polyester polymer used as the adhesive component is It is necessary to soften in an extremely short time at low temperatures and bond to the main fiber. For this reason, there is a method of using, for example, a polyester whose softening initiation temperature is significantly lowered by copolymerizing a large amount of isophthalic acid or diethylene glycol. However, since such copolymerized polyester is poor in quality, it has the disadvantage that it does not adhere sufficiently to the main fiber after a short heat treatment. In addition, when aliphatic polyester is used as a thermal adhesive component, it generally has lower thermal stability than aromatic polyester, so it easily decomposes during melt spinning, and the main body made of aromatic polyester such as PET There are problems such as low #2 adhesion strength to fibers.

As a binder fiber capable of solving such conventional problems, the present inventors previously proposed in the patent application Mei 481 dated December 22, 1986 [l] that 40 to 100 moles of the acid component in polyester. % is terephthalic acid component.

60 to 0 mol% is isophthalic acid component, the glycol component is substantially tetramethylene glycol component or hexamethylene glycol component, melting point is 160
A composite fiber composed of a polyester (^) with a low melting point below ℃ and a polyester (B) with a higher melting point than the polyester (A), wherein the polyester (^) occupies any cross section of the fiber. We have proposed a polyester thermoadhesive composite binder fiber characterized by a ratio of 10 to 70%.

This binder fiber is a polyester-based composite binder fiber, and the adhesive component is crystalline polyester. As a result of strong adhesion, a strong fiber network structure can be formed in the resulting nonwoven fabric, and a high-strength polyester nonwoven fabric can be obtained.

However, the low melting point polyester used as the adhesive component of such binder fibers needs to have a high degree of polymerization in order to obtain a high strength nonwoven fabric.

For this reason, the 31! When a tetraalkyl tatinate having condensation catalytic ability was used, the obtained low melting point polyester had a high degree of polymerization, but had an extremely deep yellow hue and could not be put to practical use.

On the other hand, if an antimony compound is used to improve the hue of a low melting point polyester, the hue of the resulting polyester is improved, but the polycondensation reaction rate is extremely slow and cannot be used in industrial production.

(Objective of the Invention) The object of the present invention is to use a low melting point polyester with a high degree of polymerization and a good color, to have excellent adhesive strength with the main fiber made of aromatic polyester such as P E 'r'. The object of the present invention is to provide a binder fiber that can be bonded in a short time, especially at low temperatures.

(Structure) As a result of studies to achieve the above object, the present inventors discovered that
By using the polycondensation catalyst proposed in Publication No. 7, that is, the reaction product of a tetraalkyl titanate and an organic carboxylic acid or its anhydride as a polycondensation catalyst, and also using a sulfonic acid metal salt, a high degree of polymerization can be achieved. It was discovered that it is possible to obtain a low melting point polyester with a high color and a good hue, and the present invention was achieved.

That is, in the present invention, 40% of the acid component constituting the polyester
-100 mol% is a terephthalic acid component, 60-0 mol% is an isophthalic acid component, the glycol component is substantially a tetramethylene glycol component or a hexamethylene glycol component, melting point is 160°C or less, intrinsic viscosity [η
]0.6 or more, the polyester contains a reaction product of a tetraalkyl tatinate and an organic carboxylic acid or its anhydride as a polycondensation catalyst, and the reaction product as a hue improver during the polycondensation reaction. The following general formula [
The binder fiber is characterized in that at least a portion of the fiber surface is made up of polyester containing a sulfonic acid metal salt represented by [I].

A-8-0-M ...... [I] In the present invention, as a bifunctional carboxylic acid compound as a raw material for polyester, terephthalic acid and/or its derivatives account for 40 to 100 mol%, 60 to 0 It is important that the adhesive component of the binder fiber be a low melting point polyester with a melting point of 160°C or less obtained by using mol% of isophthalic acid and/or its derivatives and substantially using tetramethylene glycol or hexamethylene glycol as the glycol. be.

Here, terephthalic acid and/or its derivatives are less than 40 mol%, that is, isophthalic acid and/or its derivatives are less than 60 mol%.
When the mol% is exceeded, the melting point of the resulting polyester will be 160° C. or lower, but the polyester will begin to soften at a temperature considerably lower than the melting point.

For this reason, binder fibers containing such polyester as an adhesive component, like binder fibers containing non-grade polyester as an adhesive component, do not adhere to the main fibers sufficiently after a short heat treatment, so that the final nonwoven fabric Strength decreases.

Moreover, when producing binder fibers by melt spinning, troubles such as pellets sticking to each other during the drying process of polyester pellets before spinning, or binder fibers sticking to each other after spinning tend to occur.

Furthermore, polyesters whose melting point exceeds 160° C. are not sufficiently melted at the temperatures generally used for manufacturing nonwoven fabrics and are not suitable for practical use as adhesive components for binder fibers.

As the terephthalic acid derivative or isophthalic acid derivative, dimethyl talephthalate or dimethyl isophthalate is preferable.

The low melting point polyester used in the present invention is produced by subjecting such a bifunctional carboxylic acid compound and glycol to an esterification reaction or Nisdell exchange reaction, and then polycondensing the difunctional carboxylic acid compound and glycol in the presence of a polycondensation catalyst in the presence of a sulfonic acid compound. It is obtained by reacting.

At this time, a reaction product of a tetraalkyl titanate and an organic carboxylic acid or its anhydride is used as a polycondensation catalyst.

As such tetraalkyl titanates, those having an alkyl group having 3 or 4 carbon atoms are preferable, and tetrapyl titanate, tetraisopropyl titanate, and tetrabutyl titanate are particularly preferable.

In addition, examples of the organic carboxylic acid or anhydride thereof to be reacted with the titanium compound include acetic acid, aliphatic carboxylic acid represented by penionic acid, phthalic acid, trimellitic acid, hemimellitic acid, promellitic acid, etc. Representative examples include aromatic polycarboxylic acids and acid anhydrides thereof. The reaction product of the tetraalkyl titanate and the organic carboxylic acid or its anhydride can be obtained by dissolving both in a solvent such as ethylene glycol and holding the solution at about 80° C. for about 60 minutes.

Incidentally, the infrared absorption chart of the reaction product thus obtained is shown in the above-mentioned Japanese Patent Publication No. 61-20569 and Japanese Patent Publication No. 61-20567.

Here, if a tetraalkyl titate is used alone as a polycondensation catalyst without reacting with an organic carboxylic acid or its anhydride, the resulting polyester exhibits a deep yellow color and has poor thermal stability. Further, even when titanium compounds are used, when titanium hydride or α-titanic acid is used, these titanium compounds are easily deteriorated or have low polycondensation catalytic ability, so they cannot be used for industrial production.

There is no need to particularly limit the amount of the reaction product (hereinafter sometimes referred to as a titanium compound) used as a polycondensation catalyst in the present invention, but if it is too small, a sufficient polycondensation reaction rate cannot be obtained, and If the amount is too high, the degree of polymerization of the resulting polyester will not increase sufficiently and the hue will tend to become yellow. Titanium atoms are 0.005 to 0.1 mol%, especially 0.0
An amount of 1 to 0.05 mol% is preferred.

The sulfonic acid compound as a hue improver during the polycondensation reaction used in combination with such a polycondensation catalyst has the following general formula % formula % where A is an alkyl group having 1 to 20 carbon atoms, M is a hydrogen atom, an alkali The amount of such sulfonic acid compounds, which are metals or alkaline earth metals, preferably hydrogen atoms, potassium, sodium, or calcium, and which may be used in combination of two or more, can be within a wide range. If the amount is too small, the polyester obtained will not be able to sufficiently exhibit its yellowing improvement effect, and only a polyester with insufficient thermal stability will be obtained.

On the other hand, if the amount is too large, it will precipitate as insoluble foreign matter in the polyester, causing various problems such as increased pack pressure in the spinning process, yarn breakage, and yarn breakage in the drawing process. During the initial reaction, a significant foaming phenomenon occurs, causing fatal troubles such as clogging the vacuum system.

For this reason, it is used in an amount of 1/40 to 10 moles, particularly preferably 1/20 to 5 moles, per mole of titanium atoms in the titanium compound used as a polycondensation catalyst.

The sulfonic acid compound may be added at any time before the completion of the polycondensation reaction, but it is preferably added between before and immediately after the start of the polycondensation reaction, and preferably before the start of the transesterification reaction or esterification reaction. The titanium compound and the sulfonic acid compound may be added in advance, or the titanium compound and the sulfonic acid compound may be added simultaneously, separately, or in any order.

In addition, it is preferable to add the titanium compound used as a polycondensation catalyst between the end of the transesterification reaction or esterification reaction and the start of the polycondensation reaction, and it may be added in advance before the start of the transesterification reaction or esterification reaction. good.

Like this f! The condensation reaction is continued until the resulting polyester has an intrinsic viscosity [η] of 0.6 or more, preferably 0.7 or more, particularly preferably 0.8 or more.

If the intrinsic viscosity [η] of the resulting polyester is less than 0.6, in a nonwoven fabric using a binder fiber containing such a low intrinsic viscosity, low melting point polyester as an adhesive component, the low melting point polyester may break after thermal bonding. easily, and the strength of the nonwoven fabric becomes insufficient.

Binder fibers using low melting point polyester obtained in this way can also be used for nonwoven fabrics for sanitary materials such as disposable diapers and sanitary napkins.

Since fibers used in such applications are required to have a temperature of 0 degrees, polyester to which a fluorescent brightener has been added has sometimes been used.

However, some fluorescent brighteners contain ingredients that can cause skin damage.
Since the fluorescence intensity of nonwoven fabrics is checked to confirm whether or not a fluorescent brightener is added, fibers constituting nonwoven fabrics are required to have low fluorescence intensity.

Therefore, it is preferable to add titanium dioxide to the polyester used in the present invention because the fluorescence intensity can be significantly lowered, and this decrease in fluorescence intensity is particularly remarkable in polyesters obtained by transesterification.

When such titanium dioxide is added, it is usually added to the reaction system in the form of a slurry after it is dispersed in a dispersion medium and coarse particles are removed.

Since ethylene glycol is widely used as a dispersion medium, ethylene glycol added together with titanium dioxide tends to reduce the crystallinity of the polyester obtained by copolymerization.

If tetramethylene glycol or hexamethylene glycol is used as a dispersion medium for titanium dioxide to prevent this, it will require the installation of new dispersion equipment and complicate the dispersion operation. In particular, if hexamethylene glycol is not used,
Hexamethylene glycol is solid at room temperature, and even when melted, it has a much higher viscosity than ethylene glycol.
Difficult to remove coarse particles.

Therefore, in order to add titanium dioxide in the present invention, an ethylene glycol slurry with a titanium dioxide concentration of 20% by weight or more must be prepared at a transesterification rate or esterification rate of 8%.
When the titanium dioxide content is 5% or more and the reaction system temperature is 200°C or higher and 230°C or lower, 0.0% titanium dioxide is added to the polyester.
It is preferable to add it in an amount of 3 to 2.5% by weight.
Here, if the transesterification rate or esterification rate is less than 85% and the reaction system temperature is less than 200°C, the ethylene glycol added together with titanium dioxide will copolymerize and reduce the polymer solidity and melting point. If it is added when the reaction system temperature exceeds 230° C., titanium dioxide particles tend to aggregate due to heat shock, which tends to cause an increase in back pressure and yarn breakage during spinning.

Incidentally, the titanium dioxide that can be used in the present invention may be either anatase form or rutile form.

In the present invention, 65 to 100 mol% of the bifunctional carboxylic acid compound as a raw material for polyester is terephthalic acid and/or its derivatives, 35 to 0 mol% is isophthalic acid and/or its derivatives, and the glycol is substantially Binder fibers containing, as an adhesive component, a low-melting polyester obtained using hexamethylene glycol are preferred because they can give the final nonwoven fabric a soft feel and high strength.

In this case, the content of terephthalic acid and/or its derivatives is less than 65 mol%, that is, the content of isophthalic acid and/or its derivatives is less than 35% by mole.
If it exceeds mol%, the melting point of the resulting polyester will be too low, and the strength of the final nonwoven fabric will decrease due to hot water.If the copolymer content is too large, the crystallinity of the polyester will decrease and the melting point will decrease. Since softening begins at a temperature much lower than that of the pellet, sticking of the pellet tends to occur during the drying process before spinning.

In addition, the maximum temperature in the polycondensation reaction when such raw materials are used (melting point of the obtained polyester - F70''C)
It is preferable to do the following in order to sufficiently increase the degree of polymerization of the polyester.

The low melting point polyester whose glycol component is essentially a hexamethylene glycol component obtained in this way is
The shear strength measured by the following method is 10 kl (/aa
The above is preferable because the strength of the finally obtained nonwoven fabric can be sufficiently increased.

Measuring method for shearing strength A 0.3 RAN thick film made of low melting point polyester and a 0.1 RAN thick biaxially stretched polyethylene terephthalate film were heated at a low temperature of 25°C and a relative humidity of 65%. The melting point is heated at a temperature 15°C higher than the melting point of the polyester and held at a pressure of 10 kg/- for 30 minutes for adhesion, and then the resulting laminated film is stretched at a tensile speed of 30a.
Measure the tensile breaking stress at i+/min.

In addition, it is preferable that the melting point of this low melting point polyester is 150 to 95° C. from the viewpoint of processing the binder fiber.

In the present invention, as another preferable embodiment, as a difunctional carboxylic acid compound as a raw material for polyester,
0~. 60 mol% terephthalic acid and/or its derivatives,
A binder fiber containing 60 to 40 mol% of isophthalic acid and/or a derivative thereof and further comprising a low melting point polyester obtained by substantially using tetramethylene glycol as the f&acidic component is excellent in low-temperature adhesion and is preferred.

In this case, the content of terephthalic acid and/or its derivatives is less than 40 mol%, i.e. the content of isophthalic acid and/or its derivatives is 6
If it exceeds 0 mol%, the melting point of the resulting polyester will be too low, or the crystallinity of the polyester will decrease due to too much copolymerization component, and softening will begin at a temperature much lower than the melting point, so the drying process before spinning will be difficult. There is a tendency for the beret to become stuck. On the other hand, if the content of terephthalic acid and/or its derivative exceeds 60 mol %, the melting point tends to be higher than the bonding temperature generally employed in the production of nonwoven fabrics and the like.

When such raw materials are used, it is preferable that the maximum temperature in the polycondensation reaction be lower than (melting point of the obtained polyester + 80° C.) in order to sufficiently increase the degree of polymerization of the polyester.

The low melting point polyester whose glycol component is essentially a tetramethylene glycol component obtained in this manner preferably has a melt viscosity of 1000 to 3000 voids at a temperature of (the melting point of the polyester + 100°C). If it is less than 1,000 voices, the fluidity of the low melting point polyester will be too high during heat treatment during nonwoven fabric production, and it will tend to be unable to stay at the intertwining points of the network structure of the fibers.If it exceeds 3,000 voices, the low melting point polyester In either case, the strength of the final nonwoven fabric tends to decrease because the fluidity is too low and the number of bonding points between fibers tends to decrease.

The melting point of this low melting point polyester is preferably 130 to 160° C. from the bonding surface of the binder fibers.

The low melting point polyester used in the present invention may be used alone as a binder fiber, but it is particularly preferable that the low melting point polyester is spun into a composite fiber with another polyester having a higher melting point than the low melting point polyester.

In the case of composite fibers, it goes without saying that at least a portion of the fiber surface is occupied by low melting point polyester, but in any cross section of the composite fibers, 10 to 70%,
Preferably 30-70%, particularly preferably 25-50%
is required to be a low melting point polyester.

As such a composite fiber, a core-sheath type composite fiber having a low melting point polyester as a sheath component and a high melting point polyester as a core component is preferable.

In this core/sheath type composite fiber, when a low melting point polyester whose glycol component is essentially a tetramethylene glycol component is used as the sheath component, the core component has an intrinsic viscosity [η] (in )
It is preferable to use a polyester made of polybutylene terephthalate having a polybutylene terephthalate of 0.7 or more.

In such a core/sheath type composite fiber, PE is used as a core component.
When T is used, troubles due to sticking tend to occur in the yarn spinning process, and when polybutylene lentil retalate with an intrinsic viscosity [η] of less than 0.7 is used, the strength of the final nonwoven fabric is reduced. Tend.

Nonwoven fabrics using such binder fibers are produced by cutting the binder fibers into short fibers, and then using ordinary PET fibers.
It can be obtained by mixing short fibers to form a sliver and heat-treating it under load.

The glycol used in the present invention may contain other glycol components, such as ethylene glycol, diethylene glycol, etc., within a range that does not significantly change the properties of the obtained low melting point polyester, that is, at a ratio of 10 mol% or less.

The low melting point polyester may also contain small amounts of additives such as antioxidants, fluorescent brighteners, stabilizers, ultraviolet absorbers, and the like.

(Function) According to the present invention, a titanium compound is used which has high polycondensation catalytic ability and hardly deteriorates the hue of the obtained polyester, and a sulfonic acid metal compound is used in combination as a hue improver during the polycondensation reaction. By this, a crystalline low melting point polyester having a high degree of polymerization and a good hue can be obtained.

Therefore, the binder fiber containing such a low melting point polyester as an adhesive component can firmly adhere the main fiber made of aromatic polyester such as PUT at the intertwining point between the main fiber and the binder fiber.

(Effects of the Invention) According to the binder fiber containing the crystalline low-melting polyester of the present invention as an adhesive component, a high-density nonwoven fabric can be obtained extremely efficiently, and its industrial significance is great.

(Example) Next, the present invention will be explained in further detail by giving examples.

In the examples, parts are parts by weight, and [η] is the intrinsic viscosity determined from the value measured at 30°C in orthochlorophenol solvent. This is the measured value. The higher the b value, the higher the white skin, and the lower the b value, the lower the yellowness, that is, the better the hue.

Other properties were evaluated using the methods described below.

(1) Thermal stability of the polymer The obtained polyester was held at 260°C under a nitrogen stream,
The degree of decrease in [η] for 30 minutes (hereinafter, the smaller ΔIV is, the better the thermal stability is.

(2) The obtained polyester was molded into staple fibers (6 denier x 6 m) and blended with PET staple fibers in a card (weight ratio 20:
8G) to produce a sliver, and its drawing strength was measured. A sliver prepared in the same manner was placed under a load of 5 g/-,
After heat treatment at 60° C. for 30 minutes, the pull-out strength was measured, and the adhesive strength of the binder fiber was calculated using the following formula.

Pull-out adhesive strength after heat treatment = Pull-out strength before heat treatment ('2J Measurement of melt viscosity Using Shimadzu Koka flow tester type 301, cylinder area 4-, nozzle ■, /D = 2010.5-3, extrusion After reaching the specified temperature at a heating rate of 6°C/min under the conditions of a pressure of 52.5bIr/aJ and a test $IJ of 15g, the temperature was held for 5 minutes, and the molten polymer was discharged from the nozzle at the above pressure, and the temperature was lowered by 1 plunger. The length and required time were measured and calculated using the following formula.

1 lunger descent length 3) Discharge amount (,,a) = X4
(cd) Plunger descent time (seconds) Melt viscosity (voids) = 39° 4/discharge rate Example 1° (a) Adjustment of titanium catalyst 2.5 parts of ethylene glycol and 0.0 parts of ripe water trimellitic acid.
After dissolving 8 parts, 0.7 parts of tetrabutyl titanate (1 part, 2 moles relative to trimellitic anhydride) was added dropwise, and the mixture was kept at 80° C. under normal pressure in air to react and ripen for 60 minutes. Thereafter, the mixture was cooled to room temperature, 15 parts of acetone was added, and the mixture was filtered using paper to remove precipitates, and the mixture was dry-smoked at 100° C. for 2 hours.

The titanium content of the obtained precipitate was 11.5% by weight.

(b) Preparation of titanium dioxide slurry 30 parts of titanium dioxide powder and 70 parts of ethylene glycol were mixed with stirring, and a slurry was prepared using a homogenizer. Next, the ethylene glycol slurry of titanium dioxide was prepared using a sand grinder. The slurry was further processed using a decanter-classifier rotating at high speed, and then filtered through a filter (nominal opening 1μ).6Finally, this slurry was diluted with ethylene glycol to give a concentration of 20% by weight. .

(c) Synthesis of polyester 258 parts of dimethyl terephthalate, 218 parts of hexamethylene glycol, and 023 parts of manganese acetate as a transesterification catalyst were charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, and the temperature was increased from 140°C. 240℃
3 hours after the start of the reaction, the internal temperature reached 220° C. and 75 parts of methanol was distilled out. Here, 6.45 parts of the titanium dioxide/ethylene glycol slurry prepared in (b) above was added, and the reaction was further continued. One hour after adding the slurry, the internal temperature was 240″C.
A total of 85 parts of methanol was distilled out. Here, 0.20 part of trimethyl phosphate was added as a stabilizer,
Furthermore, as a polycondensation catalyst, the precipitate obtained in the above (a) 0.11
1 part, and then 0.06 part of sodium alkylsulfonate having an average carbon number of 14 was added. The reaction mixture was transferred to a reactor equipped with a stirrer and a glycol distillation condenser, cooled to 150°C, and then heated from 150°C to 215°C.
While gradually raising the temperature to , the pressure was lowered from normal pressure to a high vacuum of 1111 IHp to carry out a polycondensation reaction. After a total polycondensation reaction time of 4 hours, a polymer with an "η" of 0.871 was produced, and the color tone of this polymer was an I7 value of 85.2. The b value is 0.6,
The melting point was 146°C. Further, the adhesive strength measured by the method described above was 28, and Δrv was 0.021.

Example 2゜Instead of 258 parts of dimethyl terephthalate in Example 1,
The same procedure as in Example 1 was carried out except that 167.7 parts of dimethyl terephthalate and 90.3 parts of dimethyl isophthalate were used, and the maximum temperature (PH-Tf) in the polycondensation reaction was 165°C [η] = 0. A polymer of 817 was obtained. Table 1 shows the physical properties of the obtained polymer.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 0.38 parts of 7'-trioxide was used as the polycondensation catalyst in place of the titanium catalyst prepared in (a), but the total weight Even when the condensation reaction time was 6 hours, [η] increased only to 0.2η, and a polymer that could be used practically as a binder fiber was not obtained.

Comparative Example 2゜In Example 1, 0.0 α-titanic acid was used as the polycondensation catalyst.
The same procedure as in Example 1 was carried out except that 5 parts of the titanium catalyst prepared in (a) was used, but even if the total polycondensation reaction time was 6 hours, [η] increased only to 0.319. Therefore, a polymer that could be used practically as a binder fiber could not be obtained.

Comparative Example 3 In Example 1, 0.07 part of tetrabutyl titanate and 0.08 part of trimellitic anhydride were used as polycondensation catalysts in place of the titanium catalyst prepared in (a) in the reaction system separately without reacting them. Example 1 was carried out in the same manner as in Example 1, except that 0.063 of sodium alkylsulfonate having an average carbon number of 14 was added thereafter. The results are shown in Table 1.

Comparative Example 4 In Example 1, 0.07 part of tetrabutyl titanate was used in place of the titanium catalyst prepared in (a) as the polycondensation catalyst, and then 0.06 part of sodium alkylsulfonate having an average carbon number of 14 was added. The same procedure as in Example 1 was carried out except for the addition. The results are shown in Table 1.

Example 3 185.5 parts of dimethyl terephthalate, 164.5 parts of dimethyl isophthalate, 243 parts of tetramethylene glycol.
8 parts, and 0.4 manganese acetate as transesterification catalyst.
4 parts were charged into a reactor equipped with a stirrer, a rectification column, and a methanol distillation condenser, heated from 135°C to 170°C, and a transesterification reaction was carried out while distilling methanol produced as a result of the reaction out of the system. Four hours after the start of the reaction, the internal temperature reached 170°C, and 115.5 parts of methanol was distilled out. Here trimethyl phosphate 0 as stabilizer
．． Added 25 parts and further added il! (above as a condensation catalyst)
After adding 0.15 part of the precipitate obtained in (a), 0.08 part of sodium alkylsulfonate having an average carbon number of 14 was added. The reaction mixture was transferred to a reactor equipped with a stirrer and a glycol distillation condenser, and heated from 170°C to 210°C.
The polycondensation reaction took 3 hours because the temperature was gradually raised to .degree. C. and the pressure was lowered from normal pressure to a high vacuum of 11 m HiJ.

The physical properties of the obtained polymer are shown in Table 2. When this polyester pellet was dried at 80°C for 20 hours, no adhesion was observed. Next, this polyester is used as a sheath, and PBT of [η] 0.80 is used as a core, and the core/sheath =
Core-sheath composite spinning was carried out at a weight ratio of 50150 and wound onto a bobbin, but no sticking of the undrawn yarn was observed. The adhesive strength of this composite fiber was measured by the method described above. The results are shown in Table 2.

Comparative Example 5 The same procedure as in Example 3 was carried out except that 0.52 parts of antimony trioxide was used as the polycondensation catalyst in place of the titanium catalyst prepared in (a), but the entire polycondensation reaction Even if the time was increased to 5 hours, [η] increased only to 0.341, and a polymer that could be used practically as a binder fiber could not be obtained.

Comparative Example 6゜The same procedure as in Example 3 was carried out except that 0.07 part of α-titanic acid was used as the polycondensation catalyst in place of the titanium catalyst prepared in (a). Even when the condensation reaction time was 5 hours, [η] increased only to 0.384, and a polymer that could be used practically as a binder fiber was not obtained.

Example 7 In Example 3, instead of the titanium catalyst prepared in (a) as a polycondensation catalyst, 0.09 part of butrabutyl titanate and 0.11 part of trimellitic anhydride were reacted separately without reacting. The same procedure as in Example 3 was carried out except that 0.08 part of sodium alkylsulfonate having an average carbon number of 14 was added to the system and then further added. The results are shown in Table 2.

Comparative Example 7 In Example 3, 0.09 part of tetrabutyl titanate was used as the polycondensation catalyst in place of the titanium catalyst prepared in (a), and then 0.08 part of sodium alkylsulfonate having an average carbon number of 14 was used. The same procedure as in Example 3 was carried out except that . The results are shown in Table 2.

Procedural amendment (voluntary) January 1986

Claims (3)

[Claims] (1) 40 to 100 mol% of the acid component constituting the polyester is a terephthalic acid component, 60 to 0 mol% is an isophthalic acid component, and the glycol component is substantially a tetramethylene glycol component or a hexamethylene glycol component. , a polyester having a melting point of 160° C. or less and an intrinsic viscosity [η] of 0.6 or more, which contains a reaction product of a tetraalkyl titanate and an organic carboxylic acid or its anhydride as a polycondensation catalyst, and a polyester containing a polycondensation catalyst. A polyester containing a sulfonic acid metal salt represented by the following general formula [1] in an amount of 1/40 to 20 moles per mole of titanium atoms in the reaction product as a hue improver during the reaction, at least on the fiber surface. A binder fiber comprising a portion of the binder fiber. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, A is an alkyl group having 1 to 20 carbon atoms, and M
is a hydrogen atom, an alkali metal, or an alkaline earth. ] (2) 65 to 100 mol% of the acid component constituting the polyester is a tephthalic acid component, 35 to 0 mol% is an isophthalic acid component, and the glycol component is substantially a hexamethylene glycol component. The binder fiber described in (1). (3) 40 to 60 mol% of the acid component constituting the polyester is a terephthalic acid component, 60 to 40 mol% is an isophthalic acid component, and the glycol component is substantially a tetramethylene glycol component. The binder fiber described in (1).