阅读说明：本技术 用于热粘合性纤维的聚酯组合物、由此实现的热粘合性复合纤维及无纺布 (Polyester composition for heat-bondable fibers, heat-bondable conjugate fibers obtained therefrom, and nonwoven fabric ) 是由 崔重铉 金棹炫 李主铉 于 2018-11-27 设计创作，主要内容包括：本发明涉及用于热粘合性纤维的聚酯组合物,更详细地,涉及具有纺成纤维的优秀的纺丝性、热粘合性,使常温下的经时变化最小化,提高储存稳定性,并且可以在实现的产品中表现出优秀的触感的用于热粘合性纤维的聚酯组合物、由此实现的热粘合性复合纤维及多孔性结构体。(The present invention relates to a polyester composition for heat-bondable fibers, and more particularly, to a polyester composition for heat-bondable fibers, which has excellent spinnability and heat-bondable properties of spun fibers, minimizes a change over time at normal temperature, improves storage stability, and can exhibit excellent touch in a product to be realized, and a heat-bondable conjugate fiber and a porous structure obtained therefrom.)

1. A polyester composition for heat-bondable fibers, characterized in that,

comprising a copolyester obtained by polycondensing an acid component containing terephthalic acid with an esterified compound obtained by reacting a diol component containing ethylene glycol, a compound represented by the following chemical formula 1 and a compound represented by the following chemical formula 2,

chemical formula 1:

chemical formula 2:

2. the polyester composition for heat-bondable fibers according to claim 1, wherein the diol component contains substantially no diethylene glycol.

3. The polyester composition for heat-bondable fibers according to claim 1, wherein the sum of the contents of the compound represented by chemical formula 1 and the compound represented by chemical formula 2 in the diol component is 30 to 45 mol%.

4. The polyester composition for heat-bondable fibers according to claim 1, wherein the acid component is contained in an amount of 1 to 10 mol% based on the acid component.

5. The polyester composition for heat-bondable fibers according to claim 1, wherein the content of the compound represented by chemical formula 1 in the diol component is larger than the content of the compound represented by chemical formula 2.

6. The polyester composition for heat-bondable fibers according to claim 1, wherein the diol component contains 20 to 40 mol% of the compound represented by chemical formula 1 and 1 to 10 mol% of the compound represented by chemical formula 2.

7. The polyester composition for heat-bondable fibers according to claim 1, wherein the polyester composition has no melting point, exhibits softening behavior, and has a glass transition temperature of 60 to 75 ℃.

8. The polyester composition for heat-bondable fibers according to claim 6, wherein the diol component contains 30 to 40 mol% of the compound represented by chemical formula 1 and 1 to 6 mol% of the compound represented by chemical formula 2.

9. The polyester composition for heat-bondable fibers according to claim 1, wherein the intrinsic viscosity is 0.500dl/g to 0.800 dl/g.

10. A polyester chip comprising the polyester composition for heat-bondable fibers according to any one of claims 1 to 9.

11. A heat-bondable composite fiber characterized by comprising:

a core portion containing a polyester-based component; and

a sheath portion surrounding the core portion and containing the polyester composition for heat-bondable fibers according to any one of claims 1 to 9.

12. A nonwoven fabric comprising the heat-bondable conjugate fiber according to claim 11 and formed into a predetermined shape.

13. The nonwoven fabric according to claim 12, wherein the nonwoven fabric is one selected from the group consisting of a mattress for an automobile, an interior material for a building, a bedding material, a heat insulating material for clothing, and an insulating material for agriculture.

Technical Field

The present invention relates to a polyester composition for heat-bondable fibers, and more particularly, to a polyester composition for heat-bondable fibers, which has excellent spinnability of spun fibers and heat-bondable properties in a wide temperature range, minimizes the change over time even under summer storage conditions, improves storage stability, and can exhibit excellent touch and dyeing properties in realized products, and a heat-bondable conjugate fiber and a nonwoven fabric realized therefrom.

Background

Generally, synthetic fibers often have limited utility due to their high melting point. In particular, in the bonding application of fibers and the like, when the adhesive is used as a core or the like or as an adhesive for pressure bonding by inserting a tape-like woven fabric, the woven fabric itself may be deteriorated by heating, and there is a problem that only a special device such as a high-frequency sewing machine can be used, so that it is expected that the bonding can be easily performed only by a general simple hot press without using the special device.

When conventional low-melting polyester fibers are used for mattresses, interior materials for automobiles, and various nonwoven fabric waddings, Hot Melt (Hot Melt) type adhesive fibers are widely used for bonding different fibers to a common fiber structure used.

For example, a low melting point polyester copolymerized with terephthalic acid (TPA) and isophthalic acid (IPA) is described in U.S. Pat. No. 4129675, and a low melting point polyester fiber realized by including isophthalic acid, diethylene glycol, to improve adhesiveness is disclosed in Korean Pat. No. 10-1216690.

However, although the conventional low-melting polyester fiber may have spinnability and adhesiveness at a certain level or more, a rigid nonwoven fabric or woven fabric structure is obtained after thermal bonding due to the ring structure of the rigidity modifier.

Also, as development is made toward a direction having a low melting point or a low glass transition temperature to express adhesive characteristics, the realized polyester has poor heat resistance, undergoes a significant change with time even under storage conditions exceeding 40 ℃ in summer, and has a problem of significantly reduced storage stability due to the occurrence of bonding between polyester chips or fibers during storage.

Therefore, the development of the following heat-bondable polyester fibers has been imminent: not only the spinnability and the adhesiveness of the conventional low-melting polyester fiber can be maintained or improved, but also the storage stability can be improved while the change with time at normal temperature is minimized while the touch and the dyeing property are remarkably improved.

Disclosure of Invention

Technical problem

The present invention has been made in view of the above problems, and an object of the present invention is to provide a polyester composition for heat-bondable fibers, a heat-bondable conjugate fiber and a nonwoven fabric obtained therefrom, the polyester composition comprising: the spun fiber has excellent spinnability, excellent heat adhesiveness and remarkably improved touch and dyeing properties in applied articles, thereby minimizing the change over time at normal temperature and improving the storage stability.

Technical scheme

In order to solve the above problems, the present invention provides a polyester composition for heat-bondable fibers, comprising a copolyester obtained by polycondensation of an acidic component containing terephthalic acid and an esterified compound obtained by reaction of a diol component containing ethylene glycol, a compound represented by the following chemical formula 1 and a compound represented by the chemical formula 2.

Chemical formula 1

Chemical formula 2

According to an embodiment of the present invention, in the above diol component, the sum of the contents of the compound represented by the above chemical formula 1 and the compound represented by the chemical formula 2 may be 30 to 45 mol%.

Also, in the above diol component, the content (mole percentage) of the compound represented by chemical formula 1 may be greater than the content (mole percentage) of the compound represented by chemical formula 2.

The diol component may contain substantially no diethylene glycol.

The acidic component may further contain 1 to 10 mol% of isophthalic acid based on the acidic component.

Also, the diol component may include 1 to 40 mol% of the compound represented by chemical formula 1 and 1 to 20 mol% of the compound represented by chemical formula 2, preferably, 20 to 40 mol% of the compound represented by chemical formula 1 and 1 to 10 mol% of the compound represented by chemical formula 2, and more preferably, 30 to 40 mol% of the compound represented by chemical formula 1 and 1 to 6 mol% of the compound represented by chemical formula 2.

The acid component may further include isophthalic acid, and the total content of the isophthalic acid, the compound represented by chemical formula 1, and the compound represented by chemical formula 2 in the copolyester may be less than 55 mol%.

The composition may have no melting point and exhibit softening behavior, and the glass transition temperature may be 60 to 75 ℃, and preferably, the glass transition temperature may be 65 to 72 ℃.

The intrinsic viscosity of the composition may be 0.500dl/g to 0.800 dl/g.

The present invention also provides a polyester chip comprising the polyester composition for heat-bondable fibers of the present invention.

Also, the present invention provides a heat-bondable composite fiber comprising: a core portion containing a polyester-based component; and a sheath portion surrounding the core portion and containing the polyester composition for a heat-bondable fiber of the present invention.

The present invention also provides a nonwoven fabric comprising the heat-bondable conjugate fiber of the present invention alone or comprising the heat-bondable conjugate fiber and a polyester fiber, and formed into a predetermined shape.

According to an embodiment of the present invention, the nonwoven fabric may be one selected from the group consisting of an automobile mattress, an interior material for construction, a bedding material, a heat insulating material for clothing, and an agricultural heat insulating material.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to exhibit excellent spinnability and thermal adhesiveness of spun fibers and also significantly improved touch and dyeability in applied articles. In addition, the change over time at normal temperature can be minimized, and the storage stability can be improved. Further, the drying time can be significantly reduced when the polyester composition is prepared into chips, thereby significantly reducing the preparation time. Therefore, the article realized by using the same can minimize the change with time even under the storage condition (for example, 40 ℃ or more) such as summer season, and has excellent storage stability, so that the deformation of the original shape of the article or the deformation in use can be prevented.

Drawings

Fig. 1 is a cross-sectional view of a composite fiber according to an embodiment of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily carry out the present invention. The present invention may be embodied in many different forms and is not limited to the embodiments set forth herein.

The polyester composition for heat-bondable fibers of the present invention comprises a copolyester obtained by polycondensation of an acidic component containing terephthalic acid and an esterified compound obtained by reaction of a diol component containing ethylene glycol, a compound represented by the following chemical formula 1, and a compound represented by the chemical formula 2.

Chemical formula 1

Chemical formula 2

First, the above-mentioned acidic component contains terephthalic acid, and may further contain an aromatic polycarboxylic acid having 6 to 14 carbon atoms, or an aliphatic polycarboxylic acid having 2 to 14 carbon atoms and/or a metal sulfonate in addition to terephthalic acid.

The aromatic polycarboxylic acid having 6 to 14 carbon atoms may be used without limitation as long as it is a known acidic component that can be used for polyester production, and preferably, it may be one or more selected from the group consisting of dimethyl terephthalate, isophthalic acid, and dimethyl isophthalate, and more preferably, it may be isophthalic acid in view of stability of reaction with terephthalic acid, ease of operation, and economy.

The aliphatic polycarboxylic acid having 2 to 14 carbon atoms may be used without limitation as long as it can be used as a known acidic component for polyester production, and may be one or more selected from the group consisting of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, citric acid, pimelic acid, azelaic acid, sebacic acid, pelargonic acid, decanoic acid, dodecanoic acid, and hexadecanoic acid, as non-limiting examples thereof.

The sulfonic acid metal salt may be sodium 3, 5-diphenylmethoxybenzenesulfonate.

On the other hand, it is preferable that the polyester composition contains no other acidic component, because the other acidic component may lower the heat resistance of the polyester composition, in addition to terephthalic acid. However, when another acidic component is further contained from the viewpoints of stability of reaction with terephthalic acid, easiness of operation and economy, it is preferable that isophthalic acid is contained, and in this case, it is preferable that isophthalic acid is contained in an amount of 1 to 10 mol% based on the acidic component. When isophthalic acid is contained in an amount of less than 1 mole percent based on the acid component, it may be difficult to exhibit the desired high thermal adhesion characteristics at lower temperatures, and when isophthalic acid is contained in an amount of more than 10 mole percent, the resulting article is hard and has a significantly reduced soft touch, and when the glass transition temperature is too low, there is a problem of reduced heat resistance. Further, in the copolyester, the total content of the compound represented by chemical formula 1, the compound represented by chemical formula 2, and isophthalic acid, which will be described later, is excessively increased, and rather, the copolyester functions as a main component capable of forming crystals, and thus it may be difficult to achieve the object of the present invention, for example, to remarkably lower the thermal adhesion property at a desired temperature.

Next, the diol component includes ethylene glycol, and a compound represented by chemical formula 1 and a compound represented by chemical formula 2.

Chemical formula 1

Chemical formula 2

First, the compound represented by the above chemical formula 1 can exhibit excellent thermal adhesive properties by reducing the crystallinity and glass transition temperature of the prepared polyester composition. Further, after the fiber is prepared, dyeing can be performed under normal pressure in the dyeing step to make the dyeing step easier, and the fiber has excellent dyeing properties, so that the washing fastness can be improved, and the touch of a formed article such as a nonwoven fabric can be improved. Preferably, the diol component may include 13 to 40 mol% of the compound represented by chemical formula 1, more preferably, 20 to 40 mol% of the compound represented by chemical formula 1, and even more preferably, 30 to 40 mol% of the compound represented by chemical formula 1. When the compound represented by chemical formula 1 is contained in an amount of less than 13 mol% based on the diol component, the spinning property is excellent, but the hot-tack temperature is increased, or the hot-tack property is lowered, and the use thereof is limited. Further, if the compound represented by chemical formula 1 is contained in an amount of more than 40 mol%, there is a possibility that the spinnability is not good and commercialization is difficult, and there is a possibility that crystallinity is increased to deteriorate the thermal adhesive property.

On the other hand, the compound represented by chemical formula 1 may be preferably contained in an amount of 20 mol% or more, whereby the heat adhesion property of the polyester composition at low temperature may be further improved together with the compound represented by chemical formula 2 described later, and there is an advantage that the drying time may be significantly shortened when the polyester composition is formed into a chip.

The compound represented by the above chemical formula 2 prevents a significant decrease in the glass transition temperature of the compound represented by the chemical formula 1 while further improving the thermal adhesive characteristics of the prepared polyester composition together with the compound represented by the above chemical formula 1, and can minimize the change over time even in a storage temperature of 40 ℃ or more, thereby improving the storage stability. Regarding the thermal adhesiveness, the thermal adhesive fiber of the polyester composition, which is realized by using the compound represented by chemical formula 2 and the compound represented by chemical formula 1 in combination, can exhibit appropriate shrinkage characteristics, and by this characteristic expression, the adhesive force can be further increased at the time of thermal adhesion, and thus, a further improved thermal adhesive characteristic can be exhibited.

Preferably, the diol component may include the compound represented by chemical formula 2 in an amount of 1 to 20 mol%, more preferably, may include the compound represented by chemical formula 2 in an amount of 1 to 10 mol%, and still more preferably, may include the compound represented by chemical formula 2 in an amount of 1 to 6 mol%.

If the compound represented by chemical formula 2 is contained in an amount of less than 1 mol% based on the diol component, it is difficult to achieve the desired improvement in heat resistance, and thus there is a concern that storage stability is poor and changes with time may be significant. Further, if the compound represented by chemical formula 2 is contained in an amount of more than 20 mol% in combination with the compound represented by chemical formula 1, the spinnability is not good, and thus the commercialization may be difficult, and if isophthalic acid is further contained, the crystallinity is sufficiently reduced, and thus there is no further effect, and the crystallinity is rather increased when the content of isophthalic acid added is increased, and thus there is a possibility that the object of the present invention is not achieved, for example, excellent thermal adhesive properties at a desired temperature are remarkably reduced. Further, when the fiber is realized, a remarkably large shrinkage property is exhibited, and thus the processing is difficult.

According to a preferred embodiment of the present invention, the sum of the contents of the compound represented by chemical formula 1 and the compound represented by chemical formula 2 contained in the diol component may be preferably 30 to 45 mol%, and more preferably 33 to 41 mol%. If the sum of the contents is less than 30 mole percent, the crystallinity of the copolyester increases, a high melting point is exhibited, or it is difficult to achieve a softening point at a low temperature, the temperature at which thermal bonding is possible rises significantly, and thus excellent thermal bonding characteristics may not be exhibited at a low temperature. Further, if the compound represented by chemical formula 2 is contained in an amount of more than 45 mol%, there is a risk of remarkably lowering polymerizability and spinnability, and the crystallinity of the prepared copolyester is rather increased, so that it is difficult to exhibit high thermal adhesive characteristics at a desired temperature.

In this case, the content (mole percentage) of the compound represented by chemical formula 1 contained in the above diol component may be greater than that of the compound represented by chemical formula 2. If the content of the compound represented by chemical formula 1 is less than or equal to that of the compound represented by chemical formula 2, it is difficult to exhibit the intended thermal bonding characteristics, and since thermal bonding can be performed only at high temperature, the use of the product to be developed is limited. Further, the film may show excessive shrinkage characteristics, which may make it difficult to process the film. And thus presents a problem of difficulty in use for the intended use.

On the other hand, the diol component may include other kinds of diol components in addition to the compound represented by chemical formula 1, the compound represented by chemical formula 2, and ethylene glycol.

The other diol component may be a known diol component used in the production of a polyester, and the present invention is not particularly limited thereto, but may be an aliphatic diol component having 2 to 14 carbon atoms, and specifically, may be one or more selected from the group consisting of 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, propylene glycol, trimethyldiol, tetramethylenediol, pentamethylene glycol, hexamethylene glycol, heptamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, undecanediol, dodecanediol, and tridecanediol. However, in order to have a desired level of heat-bonding properties and heat resistance, it is preferable that the above diol component is not included, and particularly, the diol component may not substantially include diethylene glycol. If the diol component contains diethylene glycol, the glass transition temperature is rapidly lowered, and thus a desired level of heat resistance may not be achieved even if the compound represented by chemical formula 2 is contained. In this case, the fact that the diol component contains substantially no diethylene glycol means that diethylene glycol is not intentionally added in the preparation of the copolyester, and does not mean that diethylene glycol remaining to be produced in the esterification reaction or polymerization/polycondensation reaction of the acid component and the diol component is not contained. On the other hand, according to an embodiment of the present invention, the content of the residual produced diethylene glycol contained in the polyester composition may be less than 3 weight percent of the entire composition. If the content of the residual generated diethylene glycol exceeds an appropriate level, the holding pressure is increased when spinning into a fiber, and yarn breakage is frequently induced, thus there is a problem in that the spinnability is significantly reduced.

The acid component and the diol component can be prepared into a copolyester by esterification and polymerization/condensation under the synthesis conditions known in the polyester synthesis art. In this case, the acid component and the diol component may be fed at a molar ratio of 1: 1.1 to 2.0 to react, but the reaction is not limited thereto.

On the other hand, the acid component and the glycol component may be mixed at once at the above-mentioned appropriate molar ratio and then subjected to esterification reaction and polymerization/polycondensation to prepare a copolyester, or the acid component and the glycol component may be subjected to esterification reaction and polymerization/polycondensation by adding the compound represented by chemical formula 2 to the esterification reaction between ethylene glycol and the compound represented by chemical formula 1 to prepare a copolyester, and the present invention is not particularly limited thereto.

A catalyst may also be included in the esterification reaction described above. The catalyst may be one generally used for the production of polyesters, and may be produced by using a metal cellulose catalyst, as a non-limiting example.

Further, the esterification reaction is preferably carried out at a temperature of 200 to 270 ℃ and a pressure of 1100 Torr to 1350 Torr. If the above conditions are not satisfied, there is a problem that the esterification reaction time is prolonged or the reactivity is lowered, so that an esterified compound suitable for the polycondensation reaction cannot be formed.

The polycondensation reaction can be carried out at a temperature of 250 to 300 ℃ and a pressure of 0.3 to 1.0 torr, but if the conditions are not satisfied, there may be problems such as a delay in reaction time, a decrease in polymerization degree, and initiation of thermal decomposition.

In this case, a catalyst may be further contained at the time of polycondensation reaction. In order to secure appropriate reactivity and reduce production cost, an antimony compound may be used for the above catalyst, or a phosphorus compound or the like may be used in order to prevent discoloration by thermal decomposition at high temperature.

As the antimony compound, antimony oxides such as antimony trioxide, antimony tetraoxide, antimony pentaoxide and the like, antimony halides such as antimony trisulfide, antimony trifluoride, antimony trichloride and the like, antimony triacetate, antimony benzoate, antimony stearate and the like can be used.

Preferably, the antimony compound used as the above catalyst may be used in an amount of 100ppm to 600ppm based on the total weight of the polymer obtained after polymerization.

The phosphorus compound is preferably used phosphoric acids such as phosphoric acid, monomethylphosphoric acid, trimethylphosphoric acid, tributylphosphoric acid and derivatives thereof, and more preferably trimethylphosphoric acid, triethylphosphoric acid or triphenylphosphorous acid, and the amount of the phosphorus compound to be used is preferably 100ppm to 500ppm based on the total weight of the polymer obtained after polymerization.

The intrinsic viscosity of the polyester composition of the present invention prepared by the above method may be 0.5 to 0.8 dl/g. If the intrinsic viscosity is less than 0.5dl/g, the formation of a cross section may be problematic, and if the intrinsic viscosity is more than 0.5dl/g, the holding pressure (pack) may be too high, which may cause a problem in spinnability.

The polyester composition has thermal characteristics such that it has no melting point and exhibits softening behavior, and preferably, the softening point may be 90 to 110 ℃.

The glass transition temperature of the polyester composition may be 60 to 75 ℃.

If the glass transition temperature is less than 60 ℃, the polyester chips, fibers formed by the polyester composition or articles realized therefrom greatly change with time in an environment such as summer, for example, a temperature condition exceeding 40 ℃, and there is a risk that adhesion occurs between the chips or fibers to significantly reduce storage stability. Further, when the inter-chip bonding occurs, there is a possibility that a spinning defect is caused. Further, when the fiber is realized, shrinkage characteristics are excessively exhibited, and there is a risk that thermal adhesion characteristics are rather lowered. Meanwhile, there is a problem that the time required for the process may be prolonged or the process may not be smoothly performed due to limitations of heat treatment required for a drying process after forming a chip, a post-processing process after spinning a fiber, and the like.

Further, if the glass transition temperature is more than 75 ℃, there is a risk that the heat bonding property is significantly lowered, and there is a risk that the application thereof is limited as the execution temperature of the heat bonding step is limited to a high temperature.

The polyester composition according to one embodiment of the present invention may be realized as a polyester chip, and the preparation method and the specification of the polyester chip may be according to the preparation method and the specification known in the art, and the detailed description of the present invention will be omitted herein.

As shown in fig. 1, the present invention provides a heat-bondable composite fiber comprising: a core 21; and a sheath part 20 surrounding the core part 21 and containing the polyester composition for a heat-bondable fiber of the present invention.

The polyester component forming the core portion may be a known polyester having heat resistance and mechanical strength higher than those of the sheath portion, and may be, for example, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, or the like, but is not limited thereto.

The core part and the sheath part may be compositely spun at a weight ratio of, for example, 8: 2 to 2: 8, but the ratio may be appropriately adjusted according to the purpose.

The spinning conditions, spinning equipment, and the steps of cooling and drawing the composite fiber after spinning may be performed by conditions, equipment, and steps known in the art, or after appropriately deforming, and the present invention is not particularly limited thereto.

For example, the composite fiber can be spun at a spinning temperature of 270 to 290 ℃, and can be stretched 2.5 to 4.0 times after spinning. The fineness of the conjugate fiber may be 1 to 15 deniers, and the fiber length may be 1 to 100mm, for example.

In another aspect, the present invention includes a nonwoven fabric comprising the above thermally bondable conjugate fiber.

The nonwoven fabric may be formed of the heat-bondable conjugate fiber alone or may include the heat-bondable conjugate fiber and the polyester fiber. Specifically, the heat-bondable conjugate fiber and the polyester fiber may be short fibers, and after the short fibers are mixed and opened, the nonwoven fabric may be prepared by heat treatment.

According to an embodiment of the present invention, the heat-bondable conjugate fiber and the polyester fiber may be mixed in a ratio of 3: 7 to 1: 9, but the blend ratio is not limited thereto, and may be appropriately changed in consideration of the application.

The heat treatment temperature may be 100 to 180 ℃, preferably 120 to 180 ℃, and thus more improved thermal bonding characteristics can be exhibited.

Further, the porous structure may be one selected from the group consisting of an automobile mattress, an interior material for construction, a bedding material, a heat insulating material for clothing, and an agricultural heat insulating material, for example, but is not limited thereto.

Modes for carrying out the invention

The present invention is more specifically illustrated by the following examples, but the following examples are not intended to limit the present invention, but should be construed as aiding in the understanding of the present invention.

Example 1

An ester reactant was obtained by charging 38 mol% of a compound represented by the following chemical formula 1 and 3 mol% of a compound represented by the following chemical formula 2 as diol components, 59 mol% of ethylene glycol as the remaining diol component, and 100 mol% of terephthalic acid as an acid component, and subjecting the acid component and the diol components to an esterification reaction at a temperature of 250 ℃ and a pressure of 1140 torr in a ratio of 1: 1.5, wherein the reaction rate was 97.5%. The resultant ester reactant was transferred to a polycondensation reactor, and 300ppm of antimony trioxide as a polycondensation catalyst and 150ppm of phosphoric acid as a thermal stabilizer were charged, and the polyester composition for heat-adhesive fibers comprising the resulting copolyester was obtained by gradually lowering the pressure until the final pressure reached 0.5 torr and heating to 285 ℃ to conduct a polycondensation reaction, and then the polyester composition was prepared into polyester chips having a width, a length and a height of 2mm × 4mm × 3mm by a usual method.

Then, in order to prepare a core-sheath type conjugate fiber having a core portion of polyethylene terephthalate (PET) having an intrinsic viscosity of 0.65dl/g with the polyester composition as a sheath portion, a polyester chip formed of the polyester composition and a polyethylene terephthalate chip were put into a hopper and melted, respectively, and then put into a core-sheath type spinneret, after which conjugate spinning was carried out at 275 ℃ and a spinning speed of 1000mpm so that the weight ratio of the core portion to the sheath portion became 5: 5, and then the fiber was drawn by 3.0 times to prepare a heat-bondable conjugate fiber having a fiber length of 51mm and a fineness of 4.0de as shown in table 1 below.

Chemical formula 1

Chemical formula 2

Examples 2 to 14

Polyester chips and core-sheath composite fibers using the same were prepared in the same manner as in example 1, except that the composition ratio of the monomers used for preparing the copolyester was changed as shown in the following table 1, table 2, or table 3, thereby preparing the copolyester chips and the core-sheath composite fibers using the same as shown in the following table 1, table 2, or table 3.

Comparative examples 1 to 4

Polyester chips and core-sheath composite fibers using the same were prepared in the same manner as in example 1, except that the composition ratio of the monomers used for preparing the copolyester was changed as shown in the following table 2, thereby preparing polyester chips as shown in the following table 2.

Examples of the experiments

The results of evaluating the following physical properties of the polyester chips prepared in examples and comparative examples or the core-sheath heat-bondable composite fibers are shown in tables 1 to 3 below.

1. Intrinsic viscosity

The polyester chips were melted in o-chlorophenol (Ortho-Chloro Phenol) as a solvent at 110 ℃ for 30 minutes at a concentration of 2.0g/25ml, and then kept at a constant temperature of 25 ℃ for 30 minutes, and analyzed by an automatic viscosity measuring apparatus connected to a Canon (CANON) viscometer.

2. Glass transition temperature, melting Point

The glass transition temperature and melting point were measured by a differential scanning calorimeter, and the temperature rise rate was 20 ℃ per minute as an analysis condition.

3. Drying time of polyester chip

After the prepared polyester composition was sliced (chip), the moisture content was measured in a vacuum dryer at 55 ℃ for 4 hours, and the drying time was represented by the time when the measured moisture content was 100ppm or less.

4. Short fiber storage stability

500g of the prepared core-sheath composite fiber was placed in a chamber having a temperature of 40 ℃ and a relative humidity of 45% at 2kgf/cm²After leaving for 3 days, 10 experts were asked to visually observe the fusion state between fibers, and the results were evaluated for 0 to 10 minutes on the basis of 10 minutes for no fusion and 0 minutes for all fusion. As a result, the average value was 9.0 or more, excellent (. circleincircle.), 7.0 or more and less than 9.0, normal (. DELTA.), and 5.0 or more and less than 7.0, poor (. times.).

5. Operability of spinning

In the core-sheath composite fibers spun at the same content in examples and comparative examples, the number of droplets generated in the spinning process (i.e., a mass obtained by depositing a part of a fiber bundle passing through a spinneret or irregularly depositing a fiber bundle after filament breakage) was counted by a droplet detector in the spinning operability, and the number of droplets generated in the remaining examples and comparative examples was represented by a relative percentage based on the number of droplets generated in example 1 being 100.

6. Evaluation of dye uptake

After a dyeing solution containing 2 weight percent of blue (blue) dye based on the weight of the core-sheath composite fiber was subjected to a dyeing process at a bath ratio of 1: 50 at a temperature of 90 ℃ for 60 minutes, the spectral reflectance of the dyed composite fiber in the visible region (360nm to 740nm, 10nm apart) was measured by a color measuring system of kurabao corporation, and the Total K/S value as an index of the dye uptake according to the CIE1976 standard was calculated to evaluate the dye yield.

7. Adhesive strength

The core-sheath type composite fiber and a polyethylene terephthalate short fiber (fiber length 51mm, fineness 4.0de) were mixed and opened at a ratio of 5: 5, and then heat-treated at 120 ℃, 140 ℃ and 160 ℃ to form a fiber having a grammage of 35g/m²The hot-melt nonwoven fabric of (1) was formed into a test piece having a width, length and height of 100mm × 20mm × 10mm, and then the adhesive strength was measured by a Universal Testing Machine (UTM) in accordance with the KS M ISO 36 method.

On the other hand, if the form is deformed by excessive shrinkage during the heat treatment, the adhesive strength is not evaluated, and the evaluation is "form deformation".

8. Soft touch feeling

In order to evaluate the adhesive strength, the nonwoven fabric prepared by heat treatment at a temperature of 140 ℃ was subjected to sensory examination by a group consisting of 10 experts in the same industry, and the evaluation results were differentiated as follows: when 8 or more of them were soft, the test was excellent (. circleincircle.), when 6 to 7 were soft, the test was good (. largecircle.), when 4 to 5 were soft, the test was normal (. DELTA.), and when less than 4 were soft, the test was poor (. times.).

TABLE 1

TABLE 2

TABLE 3

As shown in tables 1 to 3, it was confirmed that the drying time was significantly prolonged in the comparative examples (comparative examples 1 to 3), the spinning workability was significantly poor (comparative examples 2 and 3), the storage stability of the short fibers was very poor (comparative examples 2 and 3), and the adhesive strength evaluation was expressed as morphological change at different temperatures (comparative example 4), and thus it was confirmed that these comparative examples could not satisfy all the physical properties at the same time, but it was confirmed that the various examples exhibited all the physical properties at excellent levels.

On the other hand, in examples, example 15, which contained more of the compound represented by chemical formula 2 than the compound represented by chemical formula 1, showed morphological deformation in the evaluation of adhesive strength at different temperatures, as compared with other examples, and thus it was confirmed that it was not suitable for realizing the intended physical properties.

While one embodiment of the present invention has been described in detail, the concept of the present invention is not limited to the embodiments described in the present specification, and a person of ordinary skill in the art to understand the concept of the present invention can easily propose other embodiments by adding, changing, deleting, adding, etc. components within the same concept, and these embodiments should be included in the scope of the concept of the present invention.