JPH02104755A - Ultrafine fiber web of polyester - Google Patents

Abstract

PURPOSE:To obtain the title web suitable as ground fabric napped artificial leather having specific average fiber diameter and specific intrinsic viscosity, tenacity, excellent dyeability, flexibility and a little occurrence of polymer pilling, comprising a polyester polymer by melt blowing method. CONSTITUTION:A polyester polymer (preferably polyethylene terephthalate) is melted by an extruder 1, extruded from a spinning orifice of a die 2 while blowing a high-temperature air flow upon the as-spun fibers to give the aimed web 5 having 0.8-5.0mum average fiber diameter, 0.45-0.80, preferably 0.50-0.70 intrinsic viscosity and preferably 3.0-6.0Y value. When intrinsic viscosity of ultrafine fiber >= intrinsic viscosity of polyester-0.2 is satisfied, web having excellent weight distribution in the width direction is obtained.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a polyester ultrafine fiber web, which is particularly useful as a base fabric for raised artificial leather. There are fewer balls,
Furthermore, the present invention relates to a polyester microfiber web having a uniform date distribution in the width direction.

(Prior art/problem to be solved by the invention) The present inventors previously disclosed Japanese Patent Application Laid-open No. 53-65471,
No. 1866 and No. 53-61766 disclose that a nonwoven fabric with a luxurious feel that closely resembles natural leather is made from a nonwoven fabric in which ultrafine fiber webs with an average fiber diameter of 0.1 to 5.0 μ obtained by melt blowing are three-dimensionally entangled. It was proposed that excellent brushed artificial leather could be obtained.

Regarding the method for spinning polymers by this melt blowing method, please refer to Industrial and Engineering Chemistry (Industrial and Engineering Chemistry).
The basic device and method were disclosed in 1956, in Volume 48, No. 8 (P, 1342-1346), and according to this report,
It has been shown that polyester can be blown at air temperatures as high as 398°C to obtain webs with a fiber diameter of 0.5μ. However, when such a high gas temperature is used, thermal deterioration of polyester occurs, and the resulting ultrafine fibers have an extremely low intrinsic viscosity of 0.45 or less, resulting in only a web with low fiber strength. In addition, the raised artificial leather obtained from this web has low fiber strength and therefore has poor practical performance, particularly extremely low abrasion resistance and friction dyeing fastness. Furthermore, if thermal deterioration is carried out using high gas temperatures, a problem arises in that when attempting to obtain a wide web, unevenness in the fabric weight in the width direction is large. In order to obtain a wide web, it is necessary to spread the molten polymer in the width direction in a die, and there is a difference in die residence time between the molten polymer flowing in the center of the gou part and the molten polymer flowing at the ends. When thermal deterioration occurs in the die, the degree of decomposition differs based on this difference in residence time, and this results in uneven melt viscosity of the polymer. Therefore, in general, the melt viscosity decreases more in the part where the residence time is longer, and the amount of polymer discharged increases.
On the other hand, in the portion where the residence time is short, the j-volume melt viscosity is relatively high and the amount of polymer discharged is small, resulting in uneven fabric weight distribution of the web in the width direction. When a web or a product is dyed, it also becomes a dyed spot. Further, when polymer decomposition products are generated due to thermal decomposition, they gel and partially change the flow of the molten polymer, which also causes unevenness in area. This problem severely limits its uses, and it has not been possible to use it particularly as a base fabric for artificial leather.

As a result of intensive research aimed at solving the above-mentioned problems, the present inventors came up with the present invention and completed it.

An object of the present invention is to provide a flexible ultrafine fiber web with less polymer bead formation and high web strength.

Another object of the present invention is to provide an ultrafine fiber web that can be dyed in deep colors and has excellent color fastness.

Still another object of the present invention is to provide an ultrafine fiber web with uniform basis weight distribution in the width direction.

[Means to solve the problem]

The polyester ultrafine fiber web of the present invention is an ultrafine fiber web obtained from a polyester polymer by a melt blowing method, and has an average fiber diameter of 0.8 to 5.0 μm and a diameter of 0.4 μm.
It is characterized by being composed of ultrafine fibers having an intrinsic viscosity of 5 to 0.80.

The melt blow method in the present invention is a method in which gas is jetted such that the gas jet direction intersects the discharge direction of the molten polymer near the orifice outlet.

The polyester polymer used in the present invention may be of any type as long as it can achieve the object of the present invention, such as terephthalic acid, isophthalic acid, 1゜2-bis(4-carbophenoxy)ethane, 2゜6-naphthalene. Aromatic dicarboxylic acids such as dicarboxylic acids, adipic acid, sebacic acid,
Aliphatic dicarboxylic acids such as oxalic acid, ethylene glycol, propylene glycol, butylene glycol, 2
It can be selected from 2-bis(4-β-hydroxyethoxyphenyl)propane, neopentyl glycol, polyethylene glycol, glycerin, and condensates with glycols such as pentaerythritol. The polyester polymer may be formed from one type each of the dicarboxylic acid component and the glycol component, or one or both of the components may be composed of two or more types of compounds. Further, the polyester polymer may copolymerize or contain a matting agent, a coloring agent, a pigment, an antistatic agent, and the like. Among the polyester polymers useful in the present invention, polyethylene terephthalate is particularly excellent in practical properties and dyeability, and is therefore preferred for forming artificial leather base fabrics.

The ultrafine fiber web of the present invention obtained by the melt-blowing method is a mixed fiber having an average fiber diameter in the range of 0.8 to 5.0 μm and an appropriate fiber diameter distribution. If the average fiber diameter is less than 0.8 μm, the strength of the obtained fibers will be insufficient and, furthermore, the color development will be poor. On the other hand, the average fiber diameter is 5.
If it is 0 μ or more, it is impossible to obtain raised artificial leather having an appearance (particularly chalk mark property), feel, texture, and flexibility that closely resembles natural leather from such ultrafine fibers. In addition, since this ultrafine fiber has an extremely small fiber diameter, it is difficult to measure the average length of the fiber.
0III1 or more, often 100-300ff
It is estimated to be about +In.

The polyester ultrafine fiber of the present invention has a 0.45 to 0.80
Preferably, it has an intrinsic viscosity of 0.50 to 0.70. Therefore, the strength of the web obtained from this ultrafine fiber is high. Moreover, the raised artificial leather obtained from this web has excellent abrasion resistance and wet friction dyeing fastness. If the intrinsic viscosity is 0.45 or less, the strength of the obtained web will be low, and the abrasion resistance and wet rub color fastness of the raised artificial leather will be insufficient. On the other hand, if the intrinsic viscosity is 0.80 or more, the surface fluff of the resulting raised artificial leather will feel tangled, pilling will occur, and it will not be possible to form artificial leather from natural leather scraps.

In addition, in order to obtain an ultrafine fiber web with excellent color development and various color fastnesses, it is preferable that the Y value of this random web is 2.5 to 7.0, particularly 3.0.
It is more preferable that it is 6.0. The Y value is a value indicating the degree of color development of the web or sheet-like material, and the smaller this value is, the darker the color appears. The method for measuring this Y value will be described later. If the Y value is greater than 7.0, the web will only be dyed in a light color and will have poor light fastness, making it unsuitable for use in brushed artificial leather. On the other hand, Y
If the value is less than 2.5, the web will have a sufficiently deep color and the dye fastness will be improved, but the raised artificial leather obtained from this web will be inferior in chalk mark resistance. The Y value is almost determined by the average fiber diameter and fine structure of the polyester fiber, and the larger the average fiber diameter, the more
Furthermore, the smaller the degree of oriented crystallization, the smaller the Y value.

The ultrafine fibers of the present invention are obtained by pulling a molten polymer with a high melt viscosity with high-speed gas, so the fiber microstructure is improved compared to those obtained by conventional methods. The web of the present invention has a small water conduction shrinkage rate;
Differential scanning calorimetry (DSC) shows that the cold crystallization (primary crystallization) peak is small (sometimes it does not appear) and the melting peak is multiplexed and broad, indicating that oriented crystallization has progressed in this ultrafine fiber. It is thought that there are.

The cold crystallization energy of the web of the present invention is 6.0 cal/
It is preferably less than 4.0 cal/g, particularly less than 4.0 cal/g.

As a result, not only the web strength is high, but also various color fastnesses are excellent.

Furthermore, in the present invention, thermal deterioration of the polymer is minimized by, for example, setting the gas temperature as low as 355°C or less. The advantage is that wide webs can be produced very uniformly.

That is, if the general formula: (Intrinsic viscosity of fiber) ≧ (Intrinsic viscosity of polymer) - 0,2 is satisfied, a web with an extremely good web width distribution can be obtained. When the directional area unevenness is less than 30%, particularly 20% or less, and even 10% or less, uniform dyeability can be obtained in the width direction, which is particularly preferable for use in artificial leather.

An example of the melt blowing method of the present invention will be explained using FIGS. 1 and 2. The polyester polymer is melted by an extruder (1) and fed into the gouey (2) and extruded through a number of spinning orifices (12) arranged in a row, at the same time a heated The high-pressure gas is passed through the slots 7) (15) provided on both sides of the orifice (12).
) and blows against the flow of the extruded molten polymer, and the action of the high-speed air flow stretches the extruded molten polymer into the shape of ultrafine fibers (4) and solidifies it.

The ultrafine fibers thus formed are deposited on a screen (collector) (7) circulating between a pair of rotating rollers (6) while being agitated by airflow to form a random web (5). Form.

For example, the web of the present invention minimizes the thermal deterioration of the polymer in the Gui (2) by setting the gas temperature low, and allows the molten polymer with a relatively high melt viscosity to be reduced to 1.5K.
g/(:By injecting at a high pressure of TA-0 or higher and pulling it with the high-speed gas flow formed thereby,
Average fiber diameter 0.8-5.0μ, intrinsic viscosity 0.45-0.
80 polyester fibers can be obtained. It has been discovered that by this method, it is possible to obtain for the first time a high-quality ultrafine fiber web that has high polymer viscosity, high strength, and little occurrence of polymer beads.

Since the web of the present invention has a high polymer viscosity and highly oriented crystallization of fibers, it has high strength and is excellent in various practical performances.

For example, the brushed artificial leather obtained from this web has dramatically improved abrasion resistance and friction dyeing fastness. Furthermore, since the occurrence of polymer beads is significantly reduced, an ultrafine fiber web with a relatively large diameter (about 5 μm) can be easily obtained.

The term "polymer beads" as used herein refers to a bead-like polymer having a diameter of about 10 to 500 times the diameter of the web-constituting fibers, or a knob-like polymer formed at the ends or intermediate portions of the fibers. Many of these polymer beads are extremely small and cannot be seen with the naked eye. Therefore, polymer beads can be detected by observing them using a microscope, or by staining the web itself or after applying pressing, calendering, entangling, or other means to increase its fiber density. be able to. If a large number of polymer beads are present, the uses of the obtained ultrafine fiber web are greatly limited, and in particular, it cannot be used as a base fabric for artificial leather.

The initial intrinsic viscosity of the polyester polymer used in the present invention is
It is preferably 0.50 to 0.90. When the intrinsic viscosity exceeds 0.90, the melt viscosity of the molten polymer becomes too high, and many polymer beads may occur in the resulting web. In order to reduce the occurrence of such polymer balls, it is necessary to use a high gas temperature of 370°C or higher; however, under such temperature conditions, the thermal deterioration of the polymer becomes severe, the web viscosity decreases, and the There is no point in using a viscous polymer. Moreover, the biggest problem in this case is that unevenness in surface area occurs due to thermal deterioration of the polymer, making it difficult to obtain a uniform wide web with a width of 1 m or more.

On the other hand, when the initial intrinsic viscosity of the polyester polymer is 0.50 or less, the web viscosity becomes too low and the web strength becomes low. The brushed artificial leather obtained from such a web is
Abrasion resistance and friction dye fastness become insufficient. Therefore, the initial intrinsic viscosity of the polyester polymer is 0.50 to 0.
, 90 is preferable in order to obtain a high web strength (low occurrence of polymer beads) and a uniform wide web.

A desensitizer or other modifier may be added to this polyester polymer.

The amount of polyester polymer discharged per orifice (spinning head) is preferably 0.05 to 0.50 g/min, particularly preferably 0.10 to 0.35 g/min. If the discharge rate is less than 0.05 g/min, polymer beads are likely to occur, and at a yield of 0.50 g/min, the generation of polymer beads cannot be suppressed unless the gas temperature is raised to a high temperature of 360°C or higher. Under such high temperature conditions, the viscosity of the polymer decreases significantly.

As the blowing gas used in the melt blowing method, steam and air are advantageous in terms of cost since they cause less deterioration of the polymer.

In the present invention, the setting of gas conditions has a relatively important meaning. The lower the gas temperature, the higher the viscosity of the resulting ultrafine fibers, which significantly increases the web strength, so it is preferable. As a result, this web can be used to fabricate brushed artificial leather with improved abrasion resistance and friction dyeing fastness. Moreover, the average fiber diameter becomes larger and the shrinkage rate of the web becomes smaller. Furthermore, according to the results of thermal analysis using a differential scanning calorimeter, it is recognized that the structure has a structure in which oriented crystallization is promoted. Therefore, the dyeability of the web is improved (deep color dyeing), and various dye fastnesses such as washable dye fastness are improved. Furthermore, it becomes possible to obtain a wide web with a uniform basis weight.

However, if the gas temperature is below 290° C., the polymer will adhere to the spinning spout, making it impossible to perform stable spinning, and producing a large amount of polymer balls in the web, which is not preferable. Moreover, the fiber diameter becomes too large.

On the other hand, when the gas temperature is 355°C or higher, polymer beads hardly occur, but the intrinsic viscosity of the fibers becomes too low (too much) and the web strength becomes low. The deterioration increases, resulting in a web with large area irregularities, which is undesirable for binding for artificial leather.From the above, in the present invention, the gas temperature is 290 to 355'C.
1, particularly preferably 300 to 345"C. The gas temperature referred to in the present invention is the temperature inside the lip gas header (14).

In the manufacturing process of microfiber webs, the higher the gas pressure, the higher the web strength. Additionally, the web shrinkage rate is reduced and the fiber density is increased. Furthermore, the width of the fiber diameter distribution in the web is narrowed, and a web with an appropriate fiber diameter distribution can be obtained. Moreover, the occurrence of polymer beads in the web is drastically reduced. As a result, the raised artificial leather obtained from this web has excellent abrasion resistance, dyeability, and color fastness. Moreover, the fabric weight distribution in the width direction of the web is made uniform. In the present invention, in the gas pressure gauge inside the gas header (14), 1,
It is preferable that it is 5 kg/cJ-G or more, especially 1
．． More preferably, it is 8 to 6.0 kg/crA-G.

Since the random web of the present invention is used for artificial leather,
It is important that the micro-fine fibers have a degree of freedom for rearrangement and that the web is flexible so as to enable post-interlacing treatment. Therefore, it is necessary to prevent the fibers from being thermally fused together when forming the ultrafine fiber web. At the same time, it is necessary to collect the ultrafine fibers so that they have a uniform date distribution in the width direction. Therefore, the distance between the spinning orifice and the collection surface, that is, the collection distance is 20 to 90 cIIl.
It is preferable that it is, and it is especially preferable that it is 30-80 CIO. When the collecting distance is 20 cm or less, thermal fusion of the ultrafine fibers occurs, resulting in a hard web. on the other hand,
If the collection distance is 90 cm or more, the ultrafine fibers may converge to form lobed fibers, or the fibers may be significantly scattered by air currents, resulting in a web with large area weight irregularities, which is not preferable.

The polyester microfiber web of the present invention has high strength and
It is a high quality product that is flexible, has little polymer beads, and has a uniform basis weight distribution.It also has excellent dyeability, so it can be used for a variety of purposes such as clothing and filters. It is particularly suitable as a base fabric for back-like and suede-like artificial leathers.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

However, measurements of various physical properties described in Examples and Comparative Examples were carried out by the following methods.

K&W cffl: 20 g/cn
This value is calculated by measuring the thickness under a constant load.

j''k cm: A sample with a length of 20 cm and a width of 11 was taken, and the sample was stretched and cut using an autograph with a gripping length of 1 cm, and the maximum strength at that time was determined.

"U degree"! Y: JIS L 1079-19665.1
The measurement was carried out using the 7r4II softness A method (45° cantilever method). The numerical value indicates the sliding distance of the sample, and the smaller the value, the more flexible it is.

, -1 dedication: JIS LO823-1971
Using the friction tester described in JIS LO849-
This value was tested and evaluated using the wet friction test method described in 1971.

Ten photographs were taken at 2,000x magnification using an electron microscope at ten arbitrary locations on the Pharaoh operculum LY sample. The diameters of 10 arbitrary fibers were measured for each of the 10 photographs. A total of 100 fiber diameter measurements were obtained and the average value was calculated.

Random spots 1y1 1 OCTI continuously across the width direction of the random web
A sample of IXIOCI was cut and weighed. The average value (X) of these values and the difference between the maximum and minimum values (R
) was determined and the eye spots were calculated using the following formula.

Spot weight (%) = -X 100 If necessary, after attaching 10 to 20% polyvinyl Encore to the three-dimensionally entangled nonwoven fabric (fixing with glue),
Dry heat treatment was performed at 120 to 130°C for 5 minutes to heat set. Next, the polyvinyl alcohol was removed with hot water at 70 to 80°C to prepare a sample.

This sample was dyed with the disperse dye Kayalon r'oly.
esterNavy Blue 2G-5F200 (
10% owf (manufactured by Nippon Kayaku Co., Ltd.), 1 g/l of Disper TL (manufactured by Meisei Chemical Co., Ltd.) as a dispersant, and a bath ratio of 1:80 to 10.
It was dyed at 120° C. for 1 hour with a dye solution prepared at pH 4 to 5. Next, this stained sample was mixed with 2 g of dechlorin/
Reductive cleaning of 80 DEG C. Cl2O was carried out at a bath ratio of 1:80 to 100, followed by drying. The reflectance of the sample surface was measured using a digital colorimeter (halogen lamp light source, incident angle 45°, sensitivity 1x) manufactured by Suga Test Instruments Co., Ltd. to determine the brightness difference (ΔY).

Agony level: Phenol/tetrachloroethane (volume ratio 3 at 35°C)
/2) was measured using a mixed solvent.

R4-8 energy (ca 1) Approximately 5 cm of sample (accurately weighed) was heated at a heating rate of 20 deg/min using a differential scanning calorimeter (Model DSC-2 manufactured by PerkinElmer), and chart speed 2
It was recorded on the chart under the condition of 0 mm/min. Cold crystallization peak of the sample and indium ([n) as standard material
The energy (per unit sample weight) was determined by the gravimetric method from the melting peak obtained by measurement under the same conditions using the following.

``1 Polyethylene terephthalate, which has an especially specific viscosity of 0.65, is melted in an extruder and fed into a die (shown in Figure 2) heated to 295°C.This molten polymer is
1500 pieces per cylinder pitch - 0, 3 armφ lined up in a row
It was discharged into a high-speed steam flow from an orifice at a discharge rate of 0.15 g/min/orifice.

The temperature of the steam in the lip header (Fig. 2, 14) is 322°C, the pressure is 2.5 kg/cIiI-
It was G. The generated fiber group is placed under the Gui orifice 60c.
It was continuously collected on a moving collection surface positioned at n+ and wound up as a random web with a basis weight of 200 g/nf.

The obtained ultrafine fiber web had an average fiber diameter of 2 μ, an intrinsic viscosity of 0.55, and a cold crystallization energy of 2.9, and was of good quality with no polymer balls observed. Furthermore, the density unevenness in the middle direction of the web having a width of 1500++n++ was 5%, which was an extremely good result.

Next, this random web was placed on a wire mesh, and while suctioning from below at a vacuum degree of 50 mmHg, 3.
A continuous high-speed water stream is sprayed onto the entire surface of the sheet at a pressure of 0 kg/c+a, then 10 kg/c111
It was treated in the same way at a pressure of . The obtained sheet material has an apparent density of 0.23 kg/cd and a tensile strength of 2.2 k.
g/cm and Y value of 5.0, it was extremely flexible and had a rich sense of fulfillment.

Next, 5% polyvinyl alcohol (PV) was added to the sheet material.
A) Immersed in an aqueous solution, 15% based on the weight of the sheet
After adhering PVA, it was dried. Next, the sheet material was immersed in a 15% DMF solution of polyurethane so that the DMF solution adhesion amount was 60%, and then wet coagulation was performed in an aqueous solution, and then PVA- was extracted and removed with hot water. ,
After washing and drying, the surface was puffed with 250 mesh sandpaper, further dyed with a disperse dye, and then reduced and washed with dechlorin. When the surface of the obtained raised artificial leather was observed under a microscope, fuzz consisting of an average fiber diameter of 2 μm and an average nap length of 0.2 tmn was observed. Despite such short fluff, the nubuck-like artificial leather had remarkable chalk mark properties and was excellent in quality and performance.

The physical properties of this artificial leather are shown below.

Apparent density: 0.31g/C11l Tensile strength: 3. 0 kg/cm Flexibility: 43 degrees Wet friction dyeing fastness: Grade 3 -2 to 6 and 6 1 Among the melt blow spinning method of Example 1, the steam temperature and steam pressure were changed as shown in Table 1, and the fabric weight was 200 g. A random web of /nf was obtained.

This random web was treated in the same manner as in Example 1 to obtain an interlaced nonwoven fabric and raised artificial leather. The results are shown in Table 1.

A polyethylene terephthalate chip having an intrinsic viscosity of 0.80 was melted in an extruder, and the molten polymer was fed into a die heated to 305°C. 1.2 t of molten polymer
At a discharge rate of 0.25 g/min/orifice from 0.4 amφ orifices arranged in a row with m pitch, the air temperature is 3.
A random web having a basis weight of 150 g/rrf was formed by discharging it into an air stream injected at a 40''C2 pressure of 3.5 kg/cnl-G, and this was wound up.

This web had an average fiber diameter of 3 μm, an intrinsic viscosity of 0.68, and a cold crystallization energy of 2.5, with almost no polymer beads occurring.

This web was subjected to the same entanglement treatment as in Example 1 using high-speed water jets. The obtained nonwoven fabric has an apparent density of 0.25
g/cffl, tensile strength of 2.5 kg/cm, and Y value of 2.6, making it flexible and full of sense of fulfillment.

In addition, the physical properties of the raised artificial leather obtained by the same treatment as in the examples were as follows.

Appearance density: 0.33g/aJ Tensile strength 73.8 kg Flexibility: 450 Wet rubbing dye fastness: Grade 4

[Brief explanation of drawings]

FIG. 1 is an explanatory perspective view showing an example of an apparatus used in the melt blow process, and FIG. 2 is an explanatory cross-sectional view showing an example of a die used in the melt blow process. 1... Extruder, 2... Melt blow die, 3... Gas pipe, 4... Ultrafine fiber group,
5... Random web 6... Drive roller, 7
...Screen, 8...Calendar roll, 9...Die spinneret, 1o...Lins, 1
DESCRIPTION OF SYMBOLS 1... Molten polymer channel, 12... Spinning orifice, 13... Gas inlet, 14... Lip gas header, 15... Gas slit.

Claims (7)

[Claims] 1. An ultrafine fiber web obtained from a polyester polymer by a melt-blowing method, comprising a group of ultrafine fibers having an average fiber diameter of 0.8 to 5.0 μm and an intrinsic viscosity of 0.45 to 0.80. fiber web. 2. The polyester microfiber web according to claim 1, wherein the polyester is polyethylene terephthalate. 3. The polyester microfiber web according to claim 1, wherein the microfiber web has a Y value of 2.5 to 7.0. 4. The polyester polymer has an intrinsic viscosity of 0.50 to 0.90, and the intrinsic viscosity of the ultrafine fiber and polyester polymer is expressed by the following relational expression: (Intrinsic viscosity of ultrafine fiber) ≧ (Intrinsic viscosity of polyester polymer) ) -0.2, the polyester microfiber web according to claim 1. 5. The polyester microfiber web according to claim 1, wherein when the microfiber web is measured with a differential scanning calorimeter (DSC), its crystallization peak is small and its melting peaks are multiple. 6. The polyester microfiber web according to claim 1, wherein the web has a basis weight unevenness of 10% or less in the width direction. 7. The polyester microfiber web of claim 1, wherein said web is substantially free of polymer beads.