JPH0814058B2 - Polyphenylene sulfide meltblown nonwoven fabric and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a sheet for nonwoven fabric which is easy to handle and has excellent heat resistance and chemical resistance, particularly polyphenylene sulfide (hereinafter abbreviated as PPS) useful as a filter substrate. The present invention relates to a melt blown nonwoven fabric and a method for producing the same.

More specifically, at least part of the fibers were fused or entangled, and there was no disturbance of the sheet due to winding, rewinding, cutting, etc., and the basis weight distribution was uniform, and it had a high-performance dust collecting property. Moreover, the present invention relates to a PPS melt blown non-woven fabric containing few polymer balls and a method for producing the same.

[Prior Art] As a method for producing a PPS nonwoven fabric, a general method after melt-spinning is followed by drawing, crimping and cutting, and needle-punching, water-punching after carding, and mixing heat-bonded fibers during carding, or heat treatment, or A method in which a binder is spray-processed, or a method in which a spunbond method is used for spinning and a similar sheet-forming method is proposed.

In addition, a sheeting method has been proposed in which composite spinning is performed to obtain ultrafine PPS fibers, which is then stretched and then stretched, crimped, needle punched and water punched after carding, and then sea components are desalted. ing.

Either method has the drawback that it is difficult to handle as a non-woven fabric unless some post-treatment is applied after spinning, and that the binder, oil agent, sea component, etc. remain in the non-woven fabric.

In addition, the melt viscosity of the polymers used in these spinning processes must be at least 1000 poise or higher in the spinning process, and the molecular weight must be increased to increase the melt viscosity, or it must be three-dimensionalized by thermal crosslinking or copolymerization with trichlorobenzene. was there.

[Problems to be Solved by the Invention] An object of the present invention is to solve the drawbacks of the conventional products, and to provide a uniform PPS meltblown non-woven fabric in which the sheet is not disturbed by winding, rewinding, cutting or the like, and a method for producing the same. To do.

[Means for Solving Problems] In order to solve the above problems, the present invention has the following configuration.

(1) A non-woven fabric composed of fibers having an average fineness of 0.5 denier or less, and at least a part of the fibers being fused or entangled, and having a basis weight variation rate of 7% or less and a tensile strength of 1 kg / 5 cm or more. Characteristic PPS melt blown non-woven fabric.

(2) A method for producing a PPS meltblown non-woven fabric, which comprises using a PPS polymer having a weight average molecular weight of 20,000 to 70,000 when melt-blowing the PPS polymer into fibers.

 Hereinafter, the present invention will be described in detail.

PPS polymer has a relatively high melting point, its decomposition temperature is close to the melting point, and it easily gels, making it unsuitable for melt blown spinning.

The PPS polymer for spinning PPS meltblown nonwoven fabric according to the present invention has a relatively small molecular weight and has a weight average molecular weight of 2
Choose a linear product of about 10,000 to 70,000. Desirably, the weight average molecular weight is preferably 30,000 to 60,000.

When the weight average molecular weight is less than 20,000, the melt viscosity becomes extremely low only by making the spinning condition slightly higher than the melting point, so that the control range of the spinning condition is very narrow. Also, it becomes a non-woven fabric having a weak sheet strength.

On the other hand, if the weight average molecular weight exceeds 70,000, it is necessary to set the spinning conditions at a temperature considerably higher than the melting point, resulting in polymer decomposition and gelation, resulting in nozzle clogging and lack of spinning stability.

 The PPS nonwoven fabric is manufactured as follows.

As an example of a specific manufacturing apparatus, the apparatus shown in FIG. 1 is used.

The polymer discharged from the spinning nozzle 1 is made into fibers by the gas injected from the gas injection port 2 provided in that size. The spun fiber 3 is collected by the collecting device 4 while controlling the heat-insulating blast gas and the accompanying air.

After further applying pressure with a press roll 6, the PPS meltblown nonwoven fabric sheet 5 is wound by a winding device 8.

As will be described later, 7 is a trans vector for keeping the polymer warm.

The melt viscosity of the polymer during spinning is preferably 50 to 700 poise. It is preferably 60 to 500 poise, and more preferably 70 to 300 poise.

If it is less than 50 poise, it will be a sheet consisting of short fiber length and will be a non-woven fabric with weak strength. Therefore, if the heating gas flow is reduced, the fiber becomes brittle.

On the other hand, if the melt viscosity exceeds 700 poise, not only a large amount of high-temperature heating gas is required, but also the turbulence of the air flow causes the generation of polymer balls.

The polymer discharge amount may be 0.1 to 30 g / min / nozzle discharge amount, but the optimum value varies depending on the spinning nozzle configuration. That is, as shown in JP-A-49-10258, JP-A-49-48921, etc., in a die of a type in which heated gas is injected from both sides of a nozzle, 0.1-1.0 g / Min /
A nozzle is desirable, and more preferably 0.2 to 0.5 g / min / nozzle.

Further, as in Japanese Utility Model Publication No. 62-1260, in a die of a type in which a heating gas of a polymer and a pressurized state can be jetted from a common hole under normal pressure, 0.5 to 30 g / min / nozzle is preferable due to the fiberizing mechanism of the polymer. Desirably 1 to 20 g / min / nozzle.

0.1 g / min / nozzle or less for the type that ejects heated gas from both sides of the nozzle, and 0.5 g / min / nozzle for the type that ejects heated gas in the polymer and pressurized state from a common hole under normal pressure The following discharge amounts are not preferable because the residence time of the polymer becomes long, which causes polymer decomposition, carbide generation, and nozzle clogging. On the other hand, 1.0g / min / nozzle of the type that jets heated gas from both sides of the nozzle,
Also, in the case of 30 g / min / nozzle of a type in which heated gas of polymer and pressurized state is ejected from a common hole under normal pressure, it is necessary to make spinning conditions considerably higher than the melting point. As a result, polymer decomposition is also caused in this case. However, gelation occurs and spinning stability is lost.

As for the injection amount of the heating gas for fiberizing the polymer, it is preferable to inject the heated gas at 2.0 Nm ³ / Hr or more per 1 g of the polymer to fiberize it. When the amount of heated gas injected is less than 2.0 Nm ³ / Hr, the draft is insufficient and the fiber strength is low, resulting in a brittle non-woven sheet. For this reason, it is desirable to inject fibers of 3.0 Nm ³ / Hr or more to form fibers. It is preferable that the injection amount of the heating gas is large from the viewpoint of yarn physical properties and sheet physical properties as long as the turbulence of the air flow does not occur and the generation of polymer balls does not occur. However
When fibrous by injecting at 10.0 Nm ³ / Hr or more, turbulence of air flow occurs and generation of polymer beads is recognized. This is due to the nozzle design, and it is thought that the injection amount can be further increased if the accuracy increases.

Although PPS meltblown fibers can be obtained by the above-mentioned method, when directly manufacturing non-woven fabric, PPS has a high melting point,
When collected at a distance of 15 cm or more, there is no self-fusion or entanglement enough to maintain the sheet form by cooling with the accompanying air.

Therefore, it has been necessary to devise a method including a conventional method in order to prevent the sheet from scattering by suction and to improve the handleability of the sheet from collecting to winding.

As a method for this, by applying a linear pressure of 0.1 kg / 10 cm or more immediately after collecting the fibers, it became possible to produce a PPS meltblown nonwoven fabric with morphological stability and good handleability.

In particular, the effect is remarkable when the fiber temperature on the collecting surface of the spun fiber is maintained at 150 ° C or higher.

As a method of keeping the fiber temperature on the collection surface of the spun fiber at 150 ° C or higher, the collection distance should be short. Increase the heating gas temperature. As shown in FIG. 1, there is a method of keeping heat by providing a transvector device 7 for injecting heated gas from both sides between the nozzle and the collection. A desirable method is to inject a heated gas from both sides during this period to keep the temperature warm, etc., as well as to control the entrained air so that a uniform sheet is obtained.

When this sheet is used for filter applications, the average fineness of the sheet is 0.5 denier or less and the weight variation (C
V value: abbreviated below) is 7% or less, and the tensile strength of the sheet is preferably 1 kg / 5 cm or more.

The fineness is preferably 0.2 denier or less, more preferably 0.1 denier or less.

Above 0.5 denier, the gap between fibers becomes large,
It is not preferable because it causes microscopic unevenness of weight.

However, if it is less than 0.005 denier, the strength of the fiber is low, which is not preferable.

The unit weight variation is preferably 7% or less, preferably 0.5%
The following is good.

 If it exceeds 7%, the stability of quality may be lost.

The PPS meltblown non-woven fabric produced in this way has at least some of the constituent fibers fused or entangled, and has good morphological stability, handleability, heat resistance, and chemical resistance. A thin nonwoven sheet was obtained.

 The present invention will be described below with reference to examples.

The weight average molecular weight, CV value, measuring method of average fineness, and tensile strength are as follows.

(1) Weight average molecular weight Performed by gel permeation chromatography (GPC).

(2) CV value From the created non-woven fabric, a 10 cm square sample is analyzed for 10 samples in the width direction and 10 samples in the length direction.

(3) Average fineness Ten non-woven fabrics are randomly sampled, the position is changed at a magnification of 500 times, and three electron microscope (SEM) photographs are taken for each (30 in total).

Measure the diameter of the side of 10 fibers from 1 sheet of the photograph, make a fineness distribution table, and take the median diameter as the average fineness.

(4) Tensile strength 5 non-woven fabric samples with a width of 5 cm and a length of 15 cm are sampled and tested.
The average value of breaking strength is obtained by pulling with an autograph at 5 cm and a pulling speed of 5 cm / min.

Example 1 Example 1 Dichlorobenzene and sodium sulfide were polymerized to obtain a PPS polymer having a weight average molecular weight of 50,000.

 This PPS polymer was melt blown under the following conditions.

Spinning temperature 320 ℃ Air temperature 360 ℃ Air volume 1150Nm ³ / Hr Discharge rate 300g / min Nozzle diameter 0.2mm Nozzle pitch 1.2mm Nozzle number 834 Collection distance 15cm Linear pressure immediately after collection 2kg / 100cm Melt blow spinning is stable The obtained sheet is a partially fused and entangled melt-blown non-woven sheet made of PPS having a basis weight of 30 g / m ² and an average fiber diameter of 3 microns, and has a CV value of 6.
It was 4%.

The strength of this non-woven fabric was 5 kg / 5 cm, and it was easy to handle such as winding, rewinding, and cutting.

Example 2 In Example 1, the air temperature was 320 ° C. and the air amount was 650.
Nm ³ / Hr, collection distance 25 cm, nozzle 3 cm, parallel to the fiber discharge direction 3 cm from the side, 250 ° C air at 200 Nm ³ / Hr
The injection was kept warm and the associated air was also controlled.

Meltblown spinning is stable and the resulting sheet is a partially fused and entangled meltblown non-woven sheet made of PPS with a basis weight of 29 g / m ² and an average fiber diameter of 3.5 microns, with improved uniformity and a CV value. It was 3.2%.

The strength of this non-woven fabric was 5.3 kg / 5 cm, and it was easy to handle such as winding, rewinding and cutting.

Comparative Example 1 In Example 1, a PPS polymer having a weight average molecular weight of 10,000 was spun under the same conditions, but short fibers were formed, and the fibers were blown off easily, resulting in a non-woven fabric having a weak sheet strength. In addition, in order to lengthen the fiber length, it is necessary to keep the spinning temperature below 300 ° C, which is close to the melting point of the polymer, making it very difficult to control the spinning conditions.

Comparative Example 2 In Example 1, a PPS polymer having a weight average molecular weight of 100,000 was spun under the same conditions, but a non-woven fabric having a large fineness was obtained. A spinning temperature of 360 ° C or higher was required to obtain a non-woven fabric with an average fineness of 0.5 denier or less. Not only was the working environment poor due to polymer decomposition gas, but nozzle clogging occurred within 3 hours.

EFFECTS OF THE INVENTION Since the PPS meltblown nonwoven fabric according to the present invention has at least part of the fibers fused or entangled,
Easy to handle without disturbing the sheet due to rewinding or cutting.
Therefore, it is useful for various industrial applications as a non-woven sheet base material that makes good use of heat resistance and chemical resistance.

In particular, it is most suitable as a high-performance non-woven fabric substrate for filters with a uniform basis weight distribution.

Also, by selecting a material having a special weight average molecular weight, a high-quality PPS meltblown nonwoven fabric can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a method for producing a PPS meltblown nonwoven fabric according to the present invention. 1: Nozzle 2: Gas injection port 3: Spun fiber 4: Collection device 5: Meltblown nonwoven sheet 6: Press roll 7: Transvector device 8: Winding device

Claims (6)

[Claims] 1. A non-woven fabric comprising fibers having an average fineness of 0.5 denier or less, and at least a part of the fibers being fused or entangled, having a basis weight variation of 7% or less and a tensile strength of 1 kg / 5c.
A polyphenylene sulfide meltblown non-woven fabric characterized by having a length of at least m. 2. A method for producing a polyphenylene sulfide meltblown non-woven fabric, which comprises using a polyphenylene sulfide polymer having a weight average molecular weight of 20,000 to 70,000 when melt-blowing the polyphenylene sulfide polymer to form a spun fiber. 3. The method for producing a polyphenylene sulfide meltblown nonwoven fabric according to claim 2, wherein the polyphenylene sulfide polymer is linear. 4. The method for producing a polyphenylene sulfide meltblown non-woven fabric according to claim 2, wherein upon spinning fiber formation, heated gas is jetted from both sides during collection from the spinning nozzle to keep the temperature warm. 5. The method for producing a polyphenylene sulfide meltblown nonwoven fabric according to claim 2, wherein the fiber temperature on the collecting surface of the spun fiber is 150 ° C. or higher. 6. The method for producing a polyphenylene sulfide meltblown nonwoven fabric according to claim 2, wherein the spun fiber is applied with a linear pressure of 0.1 kg / 10 cm or more immediately after the collection.