KR20100074459A - Polyester nonwoven fabrics and preparation method thereof - Google Patents

Abstract

PURPOSE: Polyester-based nonwoven fabric and a manufacturing method thereof are provided to easily manufacture the polyester-based nonwoven fabric with good properties suitable for a filter without a separated process. CONSTITUTION: Polyester-based nonwoven fabric includes first polyester filament fiber of 30-70 weight% and second polyester filament fiber of 30-70 weight%. An external diameter of the first polyester filament fiber is 70-120μm. The external diameter of the second polyester filament fiber is smaller as much as 15-55μm than the diameter of the first polyester filament fiber. A manufacturing method of the polyester filament fiber includes step for forming a filament fiber mixture, a step for laminating the filament fiber mixture in a web shape, and a step for thermally contacting the laminated filament fiber.

Description

 Polyester nonwoven fabric and its manufacturing method {POLYESTER NONWOVEN FABRICS AND PREPARATION METHOD THEREOF}

The present invention relates to a polyester-based nonwoven fabric having a low pressure loss while showing excellent collection efficiency and a method for producing the same.

The nonwoven fabric is entangled with various fibers according to the characteristics of each other to form a sheet-shaped web, and then bonded by mechanical or physical methods.

Nonwoven fabrics have excellent performance as filters compared to materials such as woven fabrics, paper and glass fibers, and are widely used for filters due to their low cost. Accordingly, many studies have been made to improve the performance of filter nonwoven fabrics.

However, in order for the nonwoven fabric to be used as a filter material, it is necessary to have an excellent collection efficiency for filtering particles of a specific size while having a low pressure loss of the fluid passing therethrough. However, a nonwoven fabric having a low pressure loss usually does not have sufficient collection efficiency, and on the contrary, a nonwoven fabric having a high collection efficiency has a high pressure loss, and therefore, it is difficult to exhibit more desirable characteristics by being used as a filter material.

Therefore, there has been a continuous demand for the development of a filter nonwoven fabric having a low pressure loss and excellent collection efficiency. Among them, a filter which has a density gradient by laminating or attaching two or more nonwoven fabrics having different density of filament fibers. For nonwoven fabrics have been proposed.

However, in the case of such a filter nonwoven fabric, a nonwoven fabric having a different density of filament fibers must be manufactured in each process and then laminated or adhered in a separate process. Depending on the type and form, there is an inconvenience to prepare the raw materials separately.

In addition, such a non-woven fabric for the filter still exhibits some problems that the collection efficiency is not sufficient or the pressure loss is partly large.

Accordingly, the present invention can be produced in a simplified process without the need to add a separate dedicated equipment, and to provide a polyester-based nonwoven fabric having a low pressure loss while showing excellent collection efficiency.

Moreover, this invention is providing the manufacturing method of the said polyester nonwoven fabric.

The present invention is 30 to 70% by weight of the first polyester filament fibers having an outer diameter of 70 to 120㎛ cross section calculated by the following formula; And 30 to 70% by weight of a second polyester filament intermixed with the first polyester filament fiber in a single layer and having an outer diameter of a cross section as small as 15 to 55 μm than the first polyester filament fiber. An ester nonwoven fabric is provided.

[Equation]

Outer diameter of cross section of filament fiber = π diameter of cross section of filament fiber (D)

The present invention also relates to spinning and stretching a polyester polymer so that the outer diameter of the cross section calculated by the above formula is from 30 to 70% by weight of the first polyester filament fiber having a diameter of 70 to 120 µm, and as small as 15 to 55 µm. Forming a filament fiber mixture in which 30 to 70% by weight of the second polyester filament having an outer diameter in cross section is mixed; Laminating the filament fiber mixture in the form of a web by a carding method; And it provides a method for producing a polyester-based nonwoven fabric comprising the step of thermally bonding the filament fibers laminated in the web form.

Hereinafter, a polyester-based nonwoven fabric and a manufacturing method thereof according to the embodiment of the present invention will be described in detail.

According to one embodiment of the invention, 30 to 70% by weight of the first polyester filament fiber having an outer diameter of 70 to 120 μm of the cross section calculated by the following formula; And 30 to 70% by weight of a second polyester filament intermixed with the first polyester filament fiber in a single layer and having an outer diameter of a cross section as small as 15 to 55 μm than the first polyester filament fiber. Ester-based nonwovens are provided.

[Equation]

Outer diameter of cross section of filament fiber = π diameter of cross section of filament fiber (D)

The polyester nonwoven fabric is composed of two kinds of polyester filament fibers having different outer diameters, that is, different thicknesses, and includes these two kinds of polyester filament fibers in a specific content range. In particular, these two types of polyester filament fibers are not contained in separate layers, but are mixed and irregularly mixed in a single layer of nonwoven fabric.

In such a polyester-based nonwoven fabric, because of the irregular mixing of the coarse filament fibers and the thin filament fibers, the spaces present in the nonwoven fabric become irregular in a disordered state, in particular, spaces having smaller pores, and relatively Spaces with large pores are irregularly arranged on the nonwoven fabric. Because of this, fine dusts can be effectively collected through the spaces having the small pores, so that the polyester-based nonwoven fabric can exhibit excellent collection efficiency, while the air loss is good through the spaces having the large pores. I can keep it.

In particular, in the polyester-based nonwoven fabric, the thickness difference (difference in the outer diameter of the cross section) between the coarse filament fiber and the thin filament fiber and the mixing ratio thereof are limited to a specific range, so that the nonwoven fabric has excellent collection efficiency and low pressure loss. It can be seen that together.

In addition, since the nonwoven fabric includes two kinds of filament fibers together in a single layer, there is no need to install a separate process or additional equipment for manufacturing different nonwoven fabrics including each filament fiber, and a simplified manufacturing process. It can be prepared through.

Therefore, the polyester-based nonwoven fabric can be very preferably used as a filter material exhibiting excellent collection efficiency and low pressure loss.

On the other hand, the polyester-based nonwoven fabric is composed of two kinds of polyester filament fibers having different thicknesses (outer diameters of cross-sections), and substantially no other filament fibers are included. Among the first polyester filament fibers, the outer diameter of the cross section is 70 to 120 µm, and the outer diameter can be calculated by the above-described formula. In this case, the diameter (D) of the cross section of the filament fiber, when the filament fiber has a circular cross section, it can be referred to as the diameter of the circular, the filament fiber has a non-circular cross section such as oval or polygonal If so, it can be referred to as the average value of the diameter of the cross section measured in various directions. In addition, the second polyester filament fiber has an outer diameter of the cross section calculated by the above equation and method is 15 µm or more smaller than the first polyester filament fiber, and more specifically, 15 to 55 µm.

As a result of the experiments of the present inventors, when the first polyester filament fibers constituting the nonwoven fabric have a predetermined outer diameter, and the second polyester filament fibers have an outer diameter having a cross section smaller by 15 to 55 μm, the collection efficiency of the nonwoven fabric is increased. It has been found that the pressure loss can be further reduced while greatly improving, and the nonwoven fabric can be produced more easily. If the outer diameter difference between the two types of filament fibers is less than 15 μm, it was found that the improvement effect of the collection efficiency is hardly observed. On the contrary, when the difference in the outer diameter of the cross sections exceeds 55 μm, the thickness between the filament fibers is increased. The difference is so great that it becomes difficult to manufacture nonwovens commercially.

On the other hand, according to the experimental results of the present inventors, it was found that not only the difference in the thickness (outer diameter of the cross-section) between the filament fibers, but also the mixing ratio of these filament fibers can greatly affect the collection efficiency and pressure loss of the nonwoven fabric. The nonwoven fabric thus comprises 30 to 70% by weight of the first and second polyester filament fibers, respectively. If the content of the first polyester filament fiber is less than 30% by weight, the pressure loss of the nonwoven fabric may be excessively increased, which may be undesirable as a filter material, and conversely, the content of the second polyester filament fiber is 30% by weight. If it is less than%, the collection efficiency of the nonwoven fabric is excessively reduced to show the desirable performance as a filter.

In the polyester-based nonwoven fabric, each of the first and second polyester filament fibers forming the same may be made of one polyester polymer that is the same as each other, or may be made of two or more polyester polymers different from each other. For example, the first polyester filament fiber may be a polyester polymer having a melting point of 250 ° C. or higher, for example, polyethylene terephthalate, polynaphthalene terephthalate or polybutylene terephthalate or any one of copolymers thereof. Can be done. In addition, the second polyester filament fibers may be made of the same polyester polymer, or may be made of a polyester copolymer having a melting point of 20 ° C. or lower than that of the polyester polymer constituting the first polyester filament fibers.

However, when the second polyester filament fibers are made of a copolymer having a low melting point, the low melting point copolymer in the filament fibers can be more easily thermally bonded to obtain a nonwoven fabric having the filament fibers attached thereto.

In this case, as the polyester copolymer having a low melting point, a copolymer in which polyethylene terephthalate or polynaphthalene terephthalate is copolymerized with adipic acid or isophthalic acid may be used. In addition, the polyethylene terephthalate, polynaphthalene terephthalate or Any polyester copolymer having a melting point of 20 ° C. or lower than polybutylene terephthalate or a copolymer thereof can be used.

The polyester-based nonwoven fabric may have a weight per unit area of 80 to 120 g / m ² , depending on the weight per unit area of a conventional filter nonwoven fabric.

The polyester-based nonwoven fabric described above exhibits very high physical properties as a filter material as it exhibits a low pressure loss with excellent collection efficiency, and furthermore, according to the configuration in which two filament fibers are mixed in a single layer. This is simplified and no additional equipment is required. Therefore, the polyester-based nonwoven fabric can be used very effectively and economically as a filter material.

On the other hand, according to another embodiment of the invention, a method for producing a polyester-based nonwoven fabric is provided. Such a polyester-based nonwoven fabric is produced by spinning and stretching a polyester polymer to obtain 30 to 70% by weight of the first polyester filament fiber having an outer diameter of 70 to 120 µm, as calculated by the above formula, and more than 15 Forming a filament fiber mixture in which 30 to 70% by weight of the second polyester filament having an outer diameter of the cross section as small as 55 to 55 탆 is mixed; Laminating the filament fiber mixture in the form of a web by a carding method; And thermally bonding the filament fibers laminated in the web form.

That is, through this manufacturing method, it is possible to easily produce the above-described polyester-based nonwoven fabric that exhibits excellent collection efficiency and low pressure loss. In particular, a polyester-based nonwoven fabric having excellent physical properties for the filter can be easily manufactured through a simplified process without the need for a separate manufacturing process for forming two kinds of filament fibers and a nonwoven fabric comprising each of them. have.

Hereinafter, the polyester nonwoven fabric will be described in detail.

First, in the forming step of the polyester filament fibers, by spinning and stretching one or two or more polyester polymers to form the first and second polyester filament fibers having different thicknesses (outer diameter of the cross-section), through To form a filament fiber mixture, the first and second polyester filament fibers are mixed in a predetermined content range.

In this case, in order to simultaneously or sequentially form two kinds of filament fibers having different thicknesses, in the spinning apparatus having two different kinds of spinnerets corresponding to the respective filament fibers, the spinning process of the polyester polymer may be performed. Can be. However, through the above manufacturing method, since the nonwoven fabric of the form in which two kinds of filament fibers are mixed in a single layer is manufactured, these two kinds of filament fibers are formed through a separate spinning device or a separate process to It is not necessary to separately prepare nonwoven fabrics each comprising filament fibers. That is, even if the two filament fibers are formed simultaneously or sequentially in a single spinning device, they can be mixed in a single layer to produce a polyester-based nonwoven fabric having excellent physical properties as described above. It is simplified and economical as no separate dedicated device is required for each of the two filament fibers.

On the other hand, the type of polyester polymer usable for the formation of such filament fibers or the outer diameter and content range of each of the two types of filament fibers are as described above with respect to one embodiment of the invention.

In addition, in the forming process of the filament fibers, the spinning process of the polyester polymer may proceed at a spinning speed of 4,500 to 5,000m / min. In addition, the resultant filament can be sufficiently drawn using a high-pressure air drawing device to obtain the filament fibers.

Then, according to the conventional nonwoven fabric manufacturing process, the filament fiber mixture is laminated in the form of a web by the opening method, and then the filament fibers laminated in the web form are thermally bonded to each other to prepare a polyester nonwoven fabric.

In this case, in thermally bonding the filament fiber mixture, two hot / high pressure rolls (for example, calender rolls or emboss rolls) exhibiting a temperature of 150 to 250 ° C, depending on the method generally applied in the nonwoven fabric manufacturing process. Etc.), the filament fiber mixture may be pressed and thermally bonded. Alternatively, according to another embodiment, the filament fiber mixture may be thermally bonded using hot air at 150 to 250 ° C.

As described above, according to the present invention, there is provided a polyester-based nonwoven fabric and a method for producing the same, which exhibits a low pressure loss with excellent collection efficiency.

Such a polyester-based nonwoven fabric not only exhibits excellent physical properties suitable for the filter, but can be easily produced without the addition of a separate process or a dedicated device, and thus can be used as a filter material.

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to specific examples and comparative examples in order to help understanding of the present invention. However, the following examples are only intended to more clearly understand the present invention, and are not limited to the following examples of the present invention.

 EXAMPLE

Example 1

Copolymer of a polyester chip consisting of a polyethylene terephthalate polymer (first component, intrinsic viscosity: 0.655, melting point: about 254 ° C.), and a copolymer of polyethylene terephthalate and adipic acid (second component, intrinsic viscosity: 0.705, melting point: about 224 Polyester chips each having a temperature of 0 ° C.) were put into the spinning apparatus. At this time, the addition ratio of the 1st component and the 2nd component was made into the weight ratio of 1st component: 2nd component = 60:40.

The components were then melted and stretched at 288 ° C. to form first polyester filament fibers consisting of the first component and second polyester filament fibers consisting of the second component, respectively. At this time, the average diameter of the first and second polyester filament fibers were adjusted to 23㎛ and 15㎛ respectively, and the spinning process was performed. At this time, the mixing ratio of the first and second polyester filament fibers was 60:40 equal to the weight ratio of the first component: second component.

Thereafter, the mixture of the filament fibers is laminated in a web form on a moving net conveyor, given primary focusing property using a calender roll (140 ° C.), and then treated with a hot air treatment unit (222 ° C.) to form a second polyester. A polyester nonwoven fabric (weight per unit area: 100 g / m ² ) was prepared by melting and thermally bonding a portion of the filament fibers.

Examples 2 and 3 and Comparative Examples 1 and 2

A polyester-based nonwoven fabric was produced in the same manner as in Example 1, except that the mixing ratio between the first and second polyester filament fibers was changed as shown in Table 1 below.

Examples 4 and 5 and Comparative Examples 3 and 4

A polyester-based nonwoven fabric was prepared in the same manner as in Example 1, except that the average diameter of each of the first and second polyester filament fibers and the outer diameter calculated therefrom were changed as shown in Table 1 below.

Comparative Examples 5 and 6

In a similar manner to Example 1, a polyester-based nonwoven fabric made of only one of the first polyester filament fibers having the average diameter and outer diameter shown in Table 1 was prepared. At this time, the formation conditions of the filament fibers were the same as the formation conditions of the first polyester filament fibers of Example 1, only the hot air treatment temperature of the remaining nonwoven fabric manufacturing process was changed to 246 ℃.

 [Experimental Example]

For the polyester-based nonwoven fabrics prepared in Examples and Comparative Examples, the filament fiber average diameter (D), the outer diameter of the cross section, the air permeability and the collection efficiency of the nonwoven fabric were evaluated in the following manner, and the results are shown in Table 1. .

1) Filament fiber average diameter (D): Average value observed and photographed by electron microscopy of the sample filament's cross section and 20 points

2) Calculation of the outer diameter length of the filament fiber cross section (S) = π (3.14) X average diameter (D)

3) Air permeability (ccs) measuring method: ASTM D737 framing method (125Pa)

4) collection efficiency measurement

   Measurements were made using an AFC131 device from TOPAS, Germany. The standard dust used was ISO Fine (A2), and the air volume was 11.3 ㎥ / hr.

TABLE 1

division Average diameter
(Μm) Mixing ratio
(%)
Outer diameter of section
(Μm) Pressure loss
(Pa) Collection efficiency
(1.0-3.0㎛,%) Aeration
(ccs) weight
(g / m ² ) Example 1 23/15 60/40 72.2 / 47.1 30 68.8 66 100 Example 2 23/15 70/30 Homology 24 55.1 73 100 Example 3 23/15 30/70 Homology 38 72.3 64 100 Example 4 23 / 17.5 60/40 72.2 / 55.0 26 65.9 78 100 Example 5 30 / 14.3 60/40 94.2 / 45 10 66.6 105 100 Comparative Example 1 23/15 80/20 72.2 / 47.1 23 48.2 81 100 Comparative Example 2 23/15 20/80 Homology 43 65.3 55 100 Comparative Example 3 23/20 60/40 72.2 / 62.8 22 46.2 93 100 Comparative Example 4 30/10 60/40 94.2 / 31.4 23 45.8 133 100 Comparative Example 5 23 100 /- 72.2 20 45.5 96 100 Comparative Example 6 15 100 /- 47.1 48 72.8 52 100

* In Table 1, the data for the average diameter, the blended rice, and the outer diameter of the cross section are expressed as for “first polyester filament fiber / second polyester filament fiber”.

Referring to Table 1, the nonwoven fabrics of Examples 1 to 5 in which the outer diameter difference between the first and second polyester filament fibers correspond to 15 to 55 μm, and their mixing ratios satisfy 30:70 to 70:30 It has been found to exhibit low pressure loss with good collection efficiency.

On the other hand, the nonwoven fabrics of Comparative Examples 1 to 6, which do not meet the above requirements regarding the outer diameter difference and the mixing ratio, are found to be difficult to be appropriately used as the nonwoven fabric for the filter because the pressure loss is too high or the collection efficiency is low.

Claims (6)

30 to 70% by weight of the first polyester filament fiber having an outer diameter of the cross section calculated by the following equation from 70 to 120 μm; And A polyester comprising 30 to 70% by weight of a second polyester filament intermixed with the first polyester filament fiber in a single layer and having an outer diameter of a cross section as small as 15 to 55 μm than the first polyester filament fiber System nonwoven fabric. [Equation] Outer diameter of cross section of filament fiber = π diameter of cross section of filament fiber (D) The polyester-based nonwoven fabric of claim 1, wherein the first polyester filament fiber comprises at least one polyester polymer selected from the group consisting of polyethylene terephthalate, polynaphthalene terephthalate, polybutylene terephthalate and copolymers thereof. . The polyester-based nonwoven fabric of claim 2, wherein the second polyester filament fiber comprises a polyester copolymer having a melting point of 20 ° C. or lower than that of the polyester polymer included in the first polyester filament fiber. 4. The polyester nonwoven fabric of claim 3, wherein the polyester copolymer is a copolymer in which polyethylene terephthalate or polynaphthalene terephthalate is copolymerized with adipic acid or isophthalic acid. The polyester polymer was spun and stretched to have 30 to 70% by weight of the first polyester filament fiber having an outer diameter of 70 to 120 탆, and an outer diameter of the cross section smaller than 15 to 55 탆. Forming a filament fiber mixture in which 30 to 70% by weight of the second polyester filament is mixed; Laminating the filament fiber mixture in the form of a web by a carding method; And Method for producing a polyester-based nonwoven fabric comprising the step of thermally bonding the filament fibers laminated in the web form. [Equation] Outer diameter of cross section of filament fiber = π diameter of cross section of filament fiber (D) The method for producing a polyester-based nonwoven fabric according to claim 5, wherein the spinning process of the polyester polymer is carried out in a spinning apparatus having two different spinnerets for forming the first and second polyester filament fibers, respectively.