KR102213846B1 - Heat Bonded Elastic Composite Fiber For Non-Woven Fabrics - Google Patents

Abstract

The present invention relates to a heat bonded elastic composite fiber for non-woven fabrics, in which the composite fiber is formed in a sheath-core type composed of a polyester-based resin as a core portion and a polyolefin-based resin having a melting point of 20°C or more lower than that of the polyester-based resin as a sheath portion. The polyester-based resin of the core portion is composed of a hard segment of diol and dicarbonic acid or a derivative thereof, and a soft segment of polyol, wherein the diol is at least one of ethylene glycol (EG) and 1,4-butanediol (1,4-BD) having a molecular weight of 500 to 1,000, and the dicarbonic acid or the derivative thereof is composed of terephthalic acid (TPA), isophthalic acid (IPA) or an ester derivative.

Description

Heat Bonded Elastic Composite Fiber For Non-Woven Fabrics}

The present invention relates to a heat-adhesive elastic composite fiber for a nonwoven fabric, and to a heat-adhesive elastic composite fiber for a nonwoven fabric with improved elasticity by using an elastic polyester-based fiber in a core portion.

Low-density non-woven fabrics with a fabric density of 10 to 45 g/㎡ are used as surface materials for paper diapers and sanitary napkins. As the use of the nonwoven fabric is diversified, the characteristics required for the nonwoven fabric also become strict, and there has been a demand for a nonwoven fabric having excellent elasticity recovery rate.

In order to meet these demands, it is necessary to have a composite fiber that is fine and has heat adhesion, and a low melting point component provides sufficient heat adhesion strength, and in particular, has excellent elasticity recovery rate.

The elastic heat-adhesive nonwoven fabric is widely used as a sanitary nonwoven fabric, and can be manufactured using a composite fiber composed of a core portion having elasticity and a low melting point heat-adhesive sheath portion.

Polyurethane-based spandex is known as a general elastic fiber. Spandex is superior to other materials in strength, elongation and elastic recovery rate. However, spandex has disadvantages such as poor heat resistance, chlorine resistance, and light resistance. Polyester-based elastic yarns developed to compensate for these shortcomings have superior advantages over spandex in heat resistance, chlorine resistance, and light resistance, but are inferior to spandex in stiffness and elastic recovery.

In the case of spandex, it is a polyurethane series, and as shown in FIG. 1, the polyurethane is made of a hard segment made of a urethane functional group and a soft segment made of a polyol structure. Due to the flexible structure of the soft segment, high elongation can be expressed.

On the other hand, due to the strong intermolecular bonding force between neighboring polyurethane molecules by hydrogen bonding between the hydrogen atom and the oxygen atom of the urethane functional group of the hard segment, the elastic recovery force that is restored to its original state after stretching is expressed.

In the case of polyester-based elastic resin, the structure of this polyurethane was simulated, and the hard segment was replaced with a polyester functional group, and the soft segment was used with a similar polyol to achieve high elongation, but the hydrogen bonds between the polyester functional groups were The elastic recovery rate of polyester-based elastic yarn is lower than that of spandex because it is low or almost none compared to urethane.

In order to improve the low elastic recovery rate of these polyester-based elastic resins, a method of using a trifunctional or higher monomer capable of crosslinking between molecules was also proposed to increase the bonding strength between molecules, but in this case, simple crosslinking reduces elongation and improves spinning fairness. Causes deterioration.

Therefore, it is necessary to develop a heat-adhesive elastic composite fiber for nonwoven fabrics with improved elastic recovery rate and low melting point adhesion.

The present invention was invented to solve the problems of the prior art. For the purpose of the present invention, in order to improve the elastic recovery rate, elasticity by adding a bifunctional aromatic/aliphatic diecid or ester derivative thereof that increases the intermolecular bonding force of the core portion. It is to provide a heat-adhesive elastic composite fiber for nonwoven fabrics having an excellent recovery rate.

In order to solve the above problems, the present invention is a heat-adhesive elastic composite fiber for a nonwoven fabric, wherein the composite fiber is a polyester-based resin as a core part and a polyolefin-based resin having a melting point lower than the polyester-based resin by 20°C or more as a sheath part. It is formed in a cis-core type, wherein the polyester-based resin of the core part is composed of a hard segment of diol and dicarbonic acid or a derivative, a soft segment of polyol, and the diol Is at least any one of ethylene glycol (EG) and 1,4-butanediol (1,4-BD) having a molecular weight of 500 to 1,000, and the dicarboxylic acid or derivative is terephthalic acid (TPA) or terephthalic acid Consisting of rick acid (TPA), isophthalic acid (IPA) or an ester derivative, the dicarbonic acid or derivative is a bifunctional aromatic dicarboxylic acid, a bifunctional cyclic aliphatic dicarboxylic acid, or each The derivative contains 1 to 5 mol% of the total dicarbonic acid or derivative, and the polyol is poly(tetramethylene ether) glycol (PTMG), polyethylene glycol (PEG), and polyol having a molecular weight of 1,000 to 3,000. Consisting of any one of propylene glycol (PPG), esterification reaction of the dicarbonic acid or derivative and polyol as a soft segment raw material, and condensation polymerization of the reaction product with diol as the hard segment raw material To provide a heat-adhesive elastic composite fiber for nonwoven fabrics.

In addition, the present invention is a composite fiber having a weight ratio of 6:4 to 4:6 of the sheath part and the core part, or a heat-adhesive elastic composite fiber for a nonwoven fabric characterized in that the hollow ratio is 5% to 20% in the total cross-sectional area of the core part. Provides.

In addition, the present invention provides a heat-adhesive elastic composite fiber for a nonwoven fabric characterized in that the bifunctional aromatic dicarboxylic acid, the bifunctional cyclic aliphatic dicarboxylic acid or each derivative is represented by the following formula (1).

[Formula 1]

However, R ₂ is aromatic or cyclic aliphatic

R ₁ , R ₃ are alkyl or hydrogen

M is a divalent metal

In addition, the present invention provides a heat-adhesive elastic composite fiber for a nonwoven fabric, characterized in that the content of the soft segment is 40 to 70 wt% based on the total weight of the polyester-based elastic resin.

The present invention has an excellent elastic recovery rate by adding and copolymerizing a difunctional aromatic/aliphatic dieside or an ester derivative thereof capable of ionic bonding in the copolymerization of a low molecular weight diol and dicarbonic acid.

1 is a schematic diagram of a spantex elastic yarn composed of a conventional urethane-based hard segment.

Hereinafter, a preferred embodiment of the present invention will be described in detail. First, in describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the subject matter of the present invention.

The terms'about','substantially', etc. of the degree used in the present specification are used at or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are used in the sense of the present invention. To assist, accurate or absolute figures are used to prevent unfair use of the stated disclosure by unscrupulous infringers.

The present invention relates to a heat-adhesive elastic composite fiber for a nonwoven fabric. Particularly, the core part has the technical features of the present invention, and the core part is made of a polyester-based elastic resin having excellent elastic recovery rate and an elastic resin using the same, and is generally manufactured in two steps.

Diol and dicarbonic acid, which are raw materials for hard segment, and polyol, which are raw materials for soft segment, are esterified, and the reaction product is condensed to complete.

In this case, it can be prepared in two ways, and the transesterification method by reaction of dimethyl terephthalate (DMT) and ethylene glycol (EG) (DMT method) or the direct esterification method by reaction of terephthalic acid and ethylene glycol (EG) (TPA method) ) By synthesizing bis-hydroxyethyl terephthalate (BHET) and a low molecular weight condensation product of BHET and removing ethylene glycol (EG) by melting and condensation polymerization to increase the length of the molecular chain.

The present invention follows the transesterification method (DMT method) by reaction of dimethyl terephthalate (DMT) and diol, and can also be prepared by a direct esterification method (TPA method) using terephthalic acid (TPA) instead of dimethyl terephthalate. .

The diol (Diol) may be composed of at least one of ethylene glycol (EG) and 1,4-butanediol (1,4-BD) having a molecular weight of 500 to 1,000,

The dicarbonic acid or derivative may be composed of terephthalic acid (TPA) or terephthalic acid (TPA) and isophthalic acid (IPA), or an ester derivative, and among the dicarbonic acid It may be composed of at least one, or may be composed of at least any one of the dicarbonic acid ester derivatives.

In the present invention, in order to increase the elastic recovery rate, dicarbonic acid or a difunctional aromatic dicarboxylic acid as an additive to the derivative, a difunctional cyclic aliphatic dicarboxylic acid, or each derivative is used as a total dicarboxylic acid (Dicarbonic acid). acid) or derivatives of 1 to 5 mol%.

The bifunctional aromatic dicarboxylic acid, the bifunctional cyclic aliphatic dicarboxylic acid, or each derivative is characterized by the following formula (1),

[Formula 1]

Here, R ₂ is a hydrocarbon series consisting of aromatic or cyclic aliphatic, and corresponds to benzene or cyclic aliphatic, saturated without multiple bonds or unsaturated with multiple bonds. Examples of saturated cyclic aliphatic groups include cyclopropane, cyclobutane, cyclopentane, and cyclohexane. It may have multiple bonds to the cyclic aliphatic.

R ₁ , R ₃ may correspond to hydrogen or an alkyl group (C1 to C10), and M is a Group 2 metal element, preferably magnesium (Mg) and calcium (Ca).

In the present invention, the content of bifunctional aromatic dicarboxylic acid, bifunctional cyclic aliphatic dicarboxylic acid, or each derivative is 1-5 mol% of the total dicarbonic acid or derivative, 0.5 mol% If the amount is less than 5 mol%, the ionic binding force becomes too high, and a high molecular weight polyester-based elastic material cannot be obtained in the polymerization process.

Representative compounds of the bifunctional aromatic/aliphatic dieside or ester derivative thereof used in the present invention include bis-dimethyl sulfo isophthalic dieside calcium salt (BSIC).

[Formula 2]

First of all, the esterification reaction of the method for producing a polyester-based elastic resin having an excellent elastic recovery rate according to the present invention will be described. The low molecular weight diol component of butane glycol of 1,4-butanediol (1,4-BD) and Esterification reaction with dimethyl terephthalate (DMT).

As for the reaction capacity, the molar fraction of dicarbonic acid and diol is 1 to 1.0 to 1.8, and the excess diol component is mostly recovered through the decompression process during the condensation polymerization reaction. (Dicarbonic acid) and diol have a value of 30 to 99% by weight in the total elastic adhesive resin composition.

The catalyst used in the esterification reaction is selected from the group consisting of zinc acetate, sodium acetate, magnesium acetate, tetranomalbutoxy titanate, tetraisopropyl titanate, titanium oxide/siloxide microcopolymer, and nano titanate. It is one or more, and is used in the range of 15000 ppm based on 100 parts by weight of the polyester-based elastic resin. If the amount of catalyst is insufficient, the esterification reaction rate is slowed, and if excessive, the thermal stability of the polyester-based elastic adhesive resin deteriorates.

After the esterification reaction proceeds, condensation polymerization is carried out.

The oligomer solution obtained by the esterification reaction and polyol, which is a soft segment, are added together with a condensation polymerization catalyst, a thermal stabilizer, and a photooxidation stabilizer into an internal pressure, heat-resistant reactor capable of vacuum depressurization, and a pressure of 760 to 1000 Torr and 200 After distilling an excess of diol at a temperature of ~270, condensation polymerization is completed under a high vacuum with a final vacuum degree of 1 mmHg or less to obtain the polyester-based elastic bonding resin of the present invention.

Here, the polyol may be selected from one of poly(tetramethylene ether) glycol (PTMG), polyethylene glycol (PEG), or polypropylene glycol (PPG) having a molecular weight of 1,000 to 3,000, and the content is a total polyester-based elastic resin. 1 to 70% by weight can be used.

In addition, in order to maintain a high elastic recovery rate, the content of the soft segment must be maintained at 40 to 70 wt% of the total polymer weight, and if the molecular weight of the polyol is less than 1,000, the elastic properties tend to decrease, and if it exceeds 3,000, the soft segment The polymerization reaction time tends to be delayed because the length of is too long.

In polyester-based elastic materials, the content of soft segments is an important resin that exhibits elastic properties. When the content of soft segments is low, elastic repulsion increases but elongation decreases. When the content of soft segments increases, elastic repulsion decreases but elongation increases. . For optimal elastic repulsion and elongation, the content of the soft segment must be maintained in an appropriate amount, and the appropriate content of the soft segment is 40 ~ 70wt%.

In addition, the polymerization catalyst used in the condensation polymerization step is one selected from the group consisting of antimony trioxide, antimony acetate, tetranormal butoxy titanate, tetraisopropyl titanate, titanium oxide/silica oxide microcopolymer, and nano titanate. Above, it can be used in the range of 15000 ppm based on 100 parts by weight of the polyester-based elastic adhesive resin.

In the present invention, a polyolefin-based resin having a melting point lower than that of the polyester-based resin by 20°C or higher may be used as the sheath part, and the polyolefin-based resin is high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), poly One or a mixture of two or more selected from propylene and ethylene-propylene copolymers may be used.

Preferably, high-density polyethylene (HDPE) may be used, and the flow flow index (MI, Melting lndex) of the olefin-based resin is not particularly limited, but the flow flow index is 1 to 100 g/10 min, more preferably 5 to It would be desirable to be 40 g/10 min.

Features and other advantages of the present description as described above will become more apparent from the examples to be described later, and the following examples are described for illustrative purposes only and cannot be construed as limiting or limiting the protection scope of the present invention. .

Example One

As the core composition, 1.7 mol of poly(tetramethylene ether) glycol (PTMG) having a molecular weight of 2,000, 13.3 mol of butanediol, 10 mol of dimethylene terephthalate (DMT) and 0.2 mol of bis-dimethyl sulfo isophthalic dieside calcium salt (BSIC) were used. Into the reaction tank in a slurry state, the transesterification reaction proceeds while raising the temperature from 150°C to 200°C. The elastic polyester resin obtained by condensation polymerization at 250°C was used. High-density polyethylene with a flow flow index of 20 g/10 min is used as the sheath composition.

The weight ratio of the core part to the sheath part was 60:40, and each was put into a separate extruder and melted.

The two melted compositions were introduced into a conventional cis-core soft composite spinning apparatus and then spun at a spinning speed of 800 m/min. The multilayer fiber spun at a temperature equal to or higher than the glass transition temperature of the elastic polyester was stretched and aligned 3.5 times, and cut into 38 mm by applying a crimp to prepare a soft heat-adhesive composite fiber according to the present invention.

The prepared fibers were carded and thermally bonded in a chamber to prepare a 20-25GSM nonwoven fabric.

The prepared nonwoven fabric was measured for recovery after 10% deformation using an Instron tensile tester.

Example 2

It was prepared in the same manner as in Example 1, but the content of the first component was 50 wt%.

Example 3

It was prepared in the same manner as in Example 1, but a hollow nozzle spinning facility was used so that the fiber cross-sectional shape was hollow.

Example 4

It was prepared in the same manner as in Example 1, but an eccentric nozzle spinning facility was used so that the fiber cross-sectional shape was eccentric.

Comparative example One

It was prepared in the same manner as in Example 1, but PET was used as a one-component composition.

Comparative example 2

It was prepared in the same manner as in Example 2, but PP was used as a one-component composition.

delete

<Measurement method>

◎ Stretch recovery rate

-Recovery rate analysis method: After fixing one end of the yarn with a length of 15cm, maintaining the strained state for 10 minutes after 10% straining, and then comparing the length increased compared to the initial length to analyze the recovery rate.

* Elasticity recovery rate calculation formula = Recovered length/Length increased when force is applied × 100

As can be seen from the results of Table 1, in the Example, it can be seen that the elastic recovery rate of the elastic yarn increases with the addition of the bis-dimethyl sulfo isophthalic dieside calcium salt (BSIC).

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have the knowledge of.

Claims (4)

In the heat-adhesive elastic composite fiber for nonwoven fabric,
The elastic composite fiber is formed in a sheath-core type of a polyester-based resin as a core part and a polyolefin-based resin having a melting point lower than the polyester-based resin by 20°C or more as a sheath part,
The polyester-based resin of the core part is composed of a hard segment of diol and dicarbonic acid or a derivative, and a soft segment of polyol,
The diol (Diol) is at least any one of ethylene glycol (EG) and 1,4-butanediol (1,4-BD) having a molecular weight of 500 to 1,000,
The dicarbonic acid or derivative is composed of terephthalic acid (TPA), isophthalic acid (IPA) or an ester derivative,
The dicarbonic acid or derivative is a bifunctional aromatic dicarboxylic acid, a bifunctional cyclic aliphatic dicarboxylic acid, or each derivative contains 1 to 5 mol% of the total dicarbonic acid or derivative Become,
The bifunctional aromatic dicarboxylic acid, bifunctional cyclic aliphatic dicarboxylic acid or derivatives thereof are the same as in Formula 1 below,

[Formula 1]
However, R ₂ is aromatic or cyclic aliphatic
R ₁ , R ₃ are alkyl or hydrogen
M is a divalent metal

The polyol is composed of any one of poly(tetramethylene ether) glycol (PTMG), polyethylene glycol (PEG) and polypropylene glycol (PPG) having a molecular weight of 1,000 to 3,000,
A heat-adhesive elastic composite fiber for a nonwoven fabric completed by esterification reaction of the dicarbonic acid or derivative and diol as a raw material for the hard segment and condensation polymerization of the reaction product with polyol as a raw material for soft segments.
According to claim 1
The weight ratio of the sheath portion and the core portion is 6:4 to 4:6 or
Heat-adhesive elastic composite fiber for a nonwoven fabric characterized in that the core portion has a hollow ratio of 5% to 20% of the total cross-sectional area.
delete The method of claim 1,
The content of the soft segment is a heat-adhesive elastic composite fiber for a nonwoven fabric, characterized in that 40 to 70 wt% based on the total weight of the polyester resin.

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