KR20180062606A - Flame-retardant Low Melting Polyester Mono Fiber And The Fiber Assembly With Excellent Flexural Strength And Flexural Elasticity Using The Same - Google Patents

Abstract

The present invention relates to a flame-retardant polyester mono fiber having a low melting point, which produces a polyester resin having a low melting point by single spinning, wherein the polyester resin is produced by copolymerizing acidic components comprising dimethyl terephthalic acid or terephthalic acid, and dimethyl adipic acid or adipic acid, and diol components comprising 2-methyl-1,3-propanediol, 1,4-butanediol, and ethylene glycol, and in a copolymerization reaction, 4,000 to 6,000 ppm of a phosphorus flame retardant is added.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a flame-retardant low-melting-point polyester single fiber, and a fiber aggregate having excellent flexural strength and flexural elasticity using the low-

The present invention relates to a flame-retardant low melting point polyester sole fiber and a fiber aggregate using the same, which is excellent in bending strength and flexural elasticity, wherein 1,4-butanediol is added to the amorphous polymer, And more particularly to a fiber aggregate excellent in bending strength and bending elasticity using the single fiber.

Fused binder fibers are used to bond filaments or staple fibers constituting the web or sheet of the nonwoven fabric. This binder fiber should have a glass transition temperature close to that of ordinary polyethylene terephthalate fibers with a heat bonding temperature of 140 to 150 ° C. In order to do this, the crystal structure in the polymer should be eliminated and the polymer structure should be made amorphous.

Generally, polyester has excellent mechanical properties, heat resistance, and chemical resistance, and is used as a fiber and engineering plastic material. However, it has a semi-crystalline property due to its molecular structure and has a high melting point, making it difficult to use as a binder. In order to use polyester as a binder fiber, a high temperature and pressure are required in the production process, and therefore, there are many difficulties in the process. Therefore, much research has been continued to develop a polyester for a binder.

As one of the methods, there is a method of copolymerizing isophthalic acid and terephthalic acid in the synthesis of a polyester resin. In this method, isophthalic acid is added in an amount of 20 to 45 mol% based on the ester molar amount. The synthesized polyester resin has an amorphous molecular structure and thus has a final melting point ranging from 145 to 180 ° C and can be used as a polyester fiber for a binder.

In addition, when a low melting point polyester resin is synthesized by adding a flame retardant, a flame retarding effect can also be generated.

However, in the polyester resin for binder using isophthalic acid, a cyclic compound having a degree of polymerization of 2 to 3 is formed when synthesized. The cyclic compound has a melting point of about 325 DEG C and does not melt at the polyester spinning temperature, so it acts as a foreign material during spinning, shortening the pack exchange cycle. Also, since the cost of isophthalic acid is usually high, .

Diethylene glycol may be used instead of isophthalate as a copolymerization component with terephthalic acid. The polyester resin synthesized by copolymerization of diethylene glycol has a high glass transition temperature and is not smoothly stretched, There is a problem that bonding strength between fibers occurs at high temperature.

Further, a low-melting-point resin can be used as a conjugate fiber by using a low-melting-point polyester conjugate fiber and a general polyester fiber having good physical properties to the sheath portion as a core portion. In this case, there is an advantage in that the low melting point polyester conjugate fiber can be used together for the binder and the structural fiber without the need of separately using the binder fiber for bonding in the nonwoven fabric, but there is also a difficulty in the process according to the composite spinning.

A polyester resin having a low melting point and a crystalline structure may be highly valuable for use as a binder for a nonwoven fabric by a single spinning without the necessity of complex spinning.

For example, U.S. Patent No. 4,129,675 discloses a low melting point copolymer polyester copolymerized with terephthalic acid and isophthalic acid. However, the copolymer polyester according to the patent has a disadvantage in that it is economically disadvantageous in that it is thermally fused at a high temperature of 190 ° C or higher have.

In addition, U.S. Pat. No. 4,065,439 discloses low melting point copolyesters copolymerized using terephthalic acid / isophthalic acid / adipic acid (or sebacic acid) and ethylene glycol / neopentyl glycol. However, the copolyester according to the patent has a melting point of 45 to 60 占 폚 which is too low to be used as a wick for a garment, and has a disadvantage in strength and weakness.

Also, the raw material components of the copolymerized polyester according to the prior art have disadvantages that they act as defects in the molecular chain of the polyester after the copolymerization, or function as a molecular chain structure that is not linear, resulting in deterioration of crystallinity and strength.

Therefore, when such a co-polyester is used in the production of the binder fiber, the crystallinity is lowered and the binder may lose its role at a temperature above the softening point after being made into a nonwoven fabric.

Therefore, it is necessary to develop a single fiber having low melting point characteristic and a fiber aggregate having a flame retardant property and a certain physical property, while the ordinary fiber of the single spinning rather than the composite fiber as the binder fiber is lowered in crystallinity.

The present invention provides a low-melting-point polyester single fiber which is improved in crystallinity by adding 1,4-butanediol to a conventional amorphous polymer and has added flame retardancy by addition of a phosphorus flame retardant.

The present invention also provides a fiber aggregate having excellent flexural strength and bending elasticity, which is composed entirely or partially of a flame retardant low-melting-point polyester single fiber improved in crystallinity by adding 1,4-butanediol to a conventional amorphous polymer .

In order to solve the above-mentioned problems, the present invention provides a process for producing a polyester resin composition comprising an acid component consisting of dimethyl terephthalic acid or terephthalic acid, and dimethyl adipic acid or adipic acid; And a diol component composed of 2-methyl-1,3-propanediol, 1,4-butanediol and ethylene glycol, and the phosphorus-containing flame retardant Is added in an amount of 4,000 to 6,000 ppm relative to the copolymer polyester resin.

The present invention also provides a low-melting-point polyester sole fiber characterized in that the 1,4-butanediol is added in an amount of 20 to 50 mol% based on the total monomers of the copolymerized polyester.

The present invention also provides a low melting polyester single fiber characterized in that a polyfunctional component in the range of 50 to 10,000 ppm is further added to the copolymer polyester to enhance intermolecular bonding of the low melting polyester resin.

The polyfunctional component may be at least one selected from the group consisting of polycarboxylic acids, polyols, polyoxycarboxylic acids, trimellitic acid, trimesic acid, 3,3,4,4-benzophenonetetracarboxylic acid, 1,2,3,4- Butanetetracarboxylic acid and derivatives thereof, glycerin, trimethylol propane, pentaerythritol, sorbitol, and the like.

Further, the present invention provides a fiber aggregate having excellent bending strength and bending elasticity, which is wholly or partly composed of the low melting point polyester single fibers.

In the present invention, 1,4-butanediol and phosphorus-based flame retardant are added to the amorphous polymer in the existing low-melting-point polyester sole fibers to improve crystallinity and add flame retardancy.

Further, the present invention has an effect of improving the flexural strength and flexural elasticity of a fibrous aggregate composed of a low-melting-point polyester single fiber having an amorphous property and a flame retardant property added with 1,4-butanediol and a phosphorus flame retardant.

Hereinafter, preferred embodiments of the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

As used herein, the terms " about, " " substantially, " " etc. ", when used to refer to a manufacturing or material tolerance inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

The present invention relates to a low-melting-point copolymer polyester resin, which is excellent in morphological stability and has a low melting point property by regulating the content of a cyclic compound in a resin, and a nonwoven fabric using single- And bending elasticity.

The present invention relates to an acidic mixture comprising methyl terephthalic acid or terephthalic acid, and dimethyl adipic acid or adipic acid; And a diol component composed of 2-methyl-1,3-propanediol, 1,4-butanediol and ethylene glycol. The low melting point poly Ester single fibers.

According to the present invention, when a resin is prepared by using 2-methyl-1,3-propanediol, the resin does not participate in the production of a cyclic compound as a side reaction product. The productivity can be improved.

Further, the methyl group of the second carbon of 2-methyl-1,3-propanediol facilitates rotation of the polymer main chain and acts as a terminal portion of the polymer, thereby widening the free space between the main chains. This shows that the meta-structure of isophthalic acid forms a bending structure in the main chain of the polymer to prevent it from becoming a crystalline polymer and has an irregular molecular structure. Therefore, it functions very effectively in lowering the melting temperature of the polymer and destroying crystallinity.

On the other hand, the lower the melting temperature and the lower the glass transition temperature, the more effective the copolymerization component. In the case of 2-methyl-1,3-propanediol, the effect of lowering the melting temperature is large The glass transition temperature is not significantly lowered, and a glass transition temperature of 65 ° C or higher is exhibited even when the high content is introduced into the amorphous polymer. Therefore, it not only enables thermal bonding between fibers even at a low process temperature, but also has excellent form stability even at a high temperature of 100 to 130 DEG C after the production of the nonwoven fabric. In addition, the thermal properties are very similar to isophthalic acid, but the production cost can be lowered when the isophthalic acid is used instead of the relatively expensive isophthalic acid.

In the copolymerized polyester of the present invention, by using 1,4-butanediol having a high crystallinity as the second copolymerization component, the crystallinity can be maintained even during copolymerization, so that the copolymer can be thermally adhered even at a temperature as high as 5 ° C above the melting point, It is possible to obtain a binder fiber having little deformation due to strong crystallinity at a temperature.

In addition, by introducing a flexible material such as dimethyladipic acid or adipic acid, the possibility of flow of the entire molecular chain is increased, and the melting point is lowered without interfering with the crystallization of 1,4-butanediol, It is possible to improve the elasticity due to the flexible molecular chains present in the polymer main chain, thereby achieving an improved effect such as a tear property and an increase in toughness at the time of nonwoven binding.

The reason why dimethyl adipate is used to improve the flexibility of dimethyl terephthalate and molecular chain as an acid component in the present invention is that when copolymerized with 1,4-butanediol as a diol component having high crystallinity, high temperature and acidity Butanediol produced by the dehydration-condensation side reaction of 1,4-butanediol is produced as a by-product and released into the air to lower the acidity of the reaction system in order to minimize the generation of tetrahydrofuran which causes environmental problems. - butanediol to block the polymerization and to obtain the effect of increasing the toughness of the polymer main chain.

In the present invention, if the addition amount of 1,4-butanediol as the second copolymerization component is less than 20 mol% based on the molar amount of the polyester resin in the final copolymerized polyester, the adhesion strength is low at a low melting point due to a high fusion temperature. 4-butanediol becomes the main component in the diol component, and the fusion temperature rises again.

If the amount of dimethyl adipate added as the first copolymerization component is less than 2 mol% based on the molar amount of the ester in the final copolymerized polyester, the desired effect of lowering the melting point and increasing the flexibility of the molecular chain can not be obtained, and if it exceeds 30 mol% And the heat resistance is also deteriorated.

Methyl-1,3-propanediol is preferably 20 to 50 mol% based on the mole of the ester in the copolymer polyester resin. If the content is less than 20 mol%, the melting point is not sufficiently lowered, The polyester resin can not be obtained. When the amount is more than 50 mol%, the crystallinity of the polyester resin is insufficient and the effect can not be obtained. On the contrary, when the polyester resin is excessively added, it acts as a main component of the diol component, have.

In the present invention, a phosphorus-based flame retardant may be added to the copolymer composition so as to have flame-retardant properties. The phosphorus flame retardant may include the following formula (1).

[Chemical Formula 1]

(Wherein R1 and R2 are methyl, phenyl, halophenyl, alkyl, haloalkyl, or haloaryl).

The phosphorus flame retardant is preferably contained in the polyester resin in an amount of 0.3 to 0.5 wt% each.

On the other hand, the multifunctional component used in the production of the copolymerized polyester of the present invention is selected from the group consisting of polycarboxylic acids, polyols and polyoxycarboxylic acids, and in particular, trimellitic acid, trimesic acid, 3,3 ' 4'-benzophenonetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid and derivatives thereof such as acid esters and acid anhydrides thereof, glycerin, pentaerythritol and sorbitol.

At this time, the multifunctional component is preferably used in order to lower the reaction temperature during the condensation polymerization of the binder according to the present invention, to shorten the reaction time to improve color defects, and to improve the workability in the case of spinning and drawing into a fiber form, 50 to 10,000 ppm, more preferably 50 to 1,000 ppm, based on the components are added.

If the added amount of the polyfunctional component is less than 10 ppm, the desired crosslinking agent can not be attained. If the added amount exceeds 10,000 ppm, rapid crosslinking causes problems in polymerization, spinning and stretching.

The copolymer polyester containing the above-mentioned diol component and polyfunctional component has a glass transition temperature of 65 ° C or higher and is required to have durability and shape stability in a high-temperature atmosphere exposed to the sun for a long time in the outdoors, Even if the nonwoven fabric for molding is mixed with all or a part of ordinary fibers, the sagging phenomenon can be prevented in a high temperature atmosphere, and also the excellent bending strength and bending elasticity are obtained.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but these examples are only illustrative of the present invention and are not intended to limit or limit the scope of protection of the present invention.

Hereinafter, this embodiment will be described.

Example  One

30 mol% of terephthalic acid, 20% of adipic acid, 20 mol% of 1,4-butanediol and 30 mol% of ethylene glycol were added to the ester reaction tank, and the reaction was carried out at a temperature of 258 DEG C in a conventional manner to obtain an oligomer . 2-methyl-1,3-propanediol is added to the oligomer obtained in a molar amount based on the molar amount of polyethylene terephthalic acid in an amount of 1 to 4,000 as a phosphorus flame retardant, wherein R1 and R2 are methyl, (hereinafter referred to as "TMP") as a multifunctional component and subjected to transesterification at 250 ° C. in the presence of a conventional transesterification catalyst. The esterification oligomer thus obtained was charged with a conventional polycondensation catalyst, and then the polycondensation reaction was carried out by raising the temperature to 280 DEG C while gradually reducing the pressure to 0.1 mmHg. Using the polyester resin thus produced, a low melting point polyester circular single fiber was produced. After spinning at a spinning temperature of 230 캜 at a spinning speed of 900 m / min, the fiber was stretched at a stretching ratio of 3.4, crimped through a crimper, and a fiber having a fiber size of 4 Da and a fiber length of 51 mm was produced. 100% nonwoven fabric using this fiber was prepared. This nonwoven fabric has a weight of 1,300 g / m ² .

Example  2

The same as Example 1, except that the nonwoven fabric having the flame retardant low melting point polyester fibers of Example 1 at 40 wt% and the ordinary polyester fibers at 60 wt% had a weight of 1,300 g / m ² .

Comparative Example  One

The same as Example 1, except that the flame retardant was added to 8,000 ppm, and the nonwoven fabric had a weight of 1,300 g / m ² .

Comparative Example  2

The same as Example 1, but no flame retardant was added.

Comparative Example  3

Woven fabric using a conjugate fiber composed of a sheath portion having the same composition as that of the composition of Example 1 and a core portion made of ordinary polyester, and having a weight of 1,300 g / m ² .

Comparative Example  4

The nonwoven fabric having a composite fiber of Comparative Example 2 in an amount of 40% by weight and an ordinary polyester fiber in an amount of 60% by weight had a weight of 1,300 g / m ² .

*How to measure

1. Flexural strength

Flexural strength specimens were prepared according to ASTM D-790. Flexural strengths of the prepared specimens were measured using a universal testing machine (UTM) at 23 ± 2 ° C and 50 ± 5% RH for 24 hours. At this time, the cross-head speed of the universal testing machine was set at 5 mm / min

2. Flexural elasticity

Flexural elastic specimens were prepared according to ASTM D-790 and flexural elasticity was measured using Universal Material Testing Machine (UTM) at 24 ± 2 ° C and 50 ± 5% RH for 24 hours. At this time, the cross-head speed of the universal testing machine was set at 5 mm / min

3. Tensile strength

Tensile strength specimens were prepared in accordance with ASTM D-638, and tensile strengths of the specimens were measured at room temperature using an universal testing machine (UTM). At this time, the cross-head speed of the universal testing machine was set at 5 mm / min

4. Limiting Oxygen Index (LOI)

In order to evaluate the flame retardancy, it was measured according to KS-M ISO 4589-1 ~ 3 or JIS K7201 A-1. The LOI index of 27 or more is good for flame retardancy, 24 to 27 and less than 23 are considered bad.

unit Required property Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Flexural strength N Vertical 29 or more 30 30 27 30 24 27 horizontal 22 or more 22 23 20 23 15 19 Flexural elasticity MPa
Vertical 440 or more 440 460 400 440 370 400 horizontal 320 or more 320 330 290 320 290 300 The tensile strength MPa
Vertical 35 or more 35 37 32 35 28 33 horizontal 15 or more 15 17 13 15 9 14 LOI 27 or more 32 27 34 22 23 20 Fairness Good Good Good Bad Good Good Good

As shown in Table 1, Example 1 satisfies all of the required properties such as flexural strength, flexural elasticity and tensile strength when 100% of the nonwoven fabric made of only the fiber according to the present invention is applied 100% .

In Example 2, even when the fibers according to the present invention were used in an amount of 40% by weight, the same or better results were obtained as compared with Example 1, but ordinary polyester fibers not containing a phosphorus flame retardant were mixed, Is low but is in a good level.

However, in Comparative Example 1, the flame retardant content was twice as large as that in Example 1, which may cause problems in the processability. In Comparative Example 2, no flame retardant was added. In Comparative Example 3, Comparative Example 4 is a nonwoven fabric obtained by mixing a conjugate fiber with a general polyester fiber, and shows a value that is less than required properties.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

Claims (5)

Acidic components consisting of dimethyl terephthalic acid or terephthalic acid, and dimethyl adipic acid or adipic acid; And
Methyl-1,3-propanediol, 1,4-butanediol and ethylene glycol, with a low melting point polyester resin,
Wherein the phosphorus-based flame retardant is added in an amount of 4,000 to 6,000 ppm relative to the copolymer polyester resin during the copolymerization reaction.
The method according to claim 1,
Wherein the 1,4-butanediol is added in an amount of 20 to 50 mol% based on the total monomers of the copolymerized polyester.
The method according to claim 1,
Wherein the low melting point polyester sole fiber is further added with a polyfunctional component in the range of 50 to 10,000 ppm with respect to the copolymer polyester in order to strengthen the intermolecular bonding of the low melting point polyester resin.
The method of claim 3,
Wherein the polyfunctional component is at least one selected from the group consisting of polycarboxylic acid, polyol, polyoxycarboxylic acid, trimellitic acid, trimesic acid, 3,3,4,4-benzophenonetetracarboxylic acid, 1,2,3,4-butanetetracarboxylic acid And derivatives thereof, glycerin, trimethylol propane, pentaerythritol, sorbitol, and the like.
A fiber aggregate comprising all or a part of the low melting point polyester single fibers according to any one of claims 1 to 4 and having excellent flexural strength and bending elasticity.