JP2849752B2 - Surface treatment method for non-woven fabric for filter cloth - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for surface-treating nonwoven fabrics, and more particularly to a method for surface-treating nonwoven fabrics for filter cloth used in industrial materials, particularly bag filters.

(Prior art) Conventionally, polyester fibers and aramid fibers have been used as filter cloths for the above bag filters because of their high heat resistance, and a non-woven fabric made of these fibers is subjected to a hot roll press treatment to smooth the surface. Used as a filter cloth.

However, since aramid fiber has difficulty in chemical resistance, especially in acid resistance, in terms of heat resistance, it has recently become difficult to use polyphenylene sulfide (PPS) fiber, a kind of functional polymer. Attempts have been made to use it.

The non-woven fabric containing such PPS fibers is not subjected to any surface treatment, or even if the surface is treated, the surface is finished only with a hot roll, or is subjected to surface fluffing by a gas flame. Use for cloth has been made.

(Problems to be Solved by the Invention) However, if the surface treatment is not performed as described above, or even if it is performed, the filter cloth formed only by hot pressing removes dust adhering to the filter cloth in the dust collector. When
In many cases, the wiping performance is inferior to that of the surface treatment.

Also, in surface processing by contact melting with a heating device, PPS
PPS melted due to the fact that the melt viscosity of the fiber itself is higher than conventional polyester fibers and aramid fibers
There has been a situation where it is extremely difficult to obtain a stable surface state in which a lump of resin does not collapse and remains on the nonwoven fabric.

Further, those obtained by burning the fluffy fibers on the surface of these nonwoven fabrics by gas flame also had a black residue remaining on the surface, and there was a high probability of occurrence of burn spots, and good smooth surface properties could not be obtained.

The present invention addresses the actual situation as described above, aims to obtain a smooth surface more reliably, and makes it easy to control the intensity of radiant heat energy by using indirect heating by an infrared heater, and to perform water cooling. The purpose is to stably produce a smooth surface state suitable as a filter cloth by using a roll, thereby forming a surface state as if a porous film is stuck on the surface, and thereby to enhance dust releasability. is there.

(Means for Solving the Problems) That is, a feature of the present invention that meets the above-mentioned object is that polyphenylene sulfide (PP
S) The fiber web containing fibers is subjected to needle punching, and the formed nonwoven fabric is used as a material. The surface is heated and melted using an infrared heater, then hot pressed with a hot roll, and subsequently cooled with a water-cooled roll to smooth out. To form an excellent surface condition.

Further, in the invention according to claim 2, in forming the surface state, specifically, the surface state is changed from a state where a porous film is stuck to a state where only a part of the nonwoven fabric is melted. The method is characterized in that the intensity of radiant heat energy received by the needle-punched nonwoven fabric is appropriately controlled.

It is to be noted that, as a matter of course, PPS fibers (melting point 289 ° C.) are included as constituent fibers of the nonwoven fabric material subjected to the surface treatment according to the present invention, but those containing 50% by weight to 100% by weight of PPS fibers are preferred. is there.

(Action) By performing the above processing method, it is possible to obtain a smooth surface state that is difficult to obtain by contact heating even with the high melt viscosity of the PPS fiber itself, and it is possible to obtain surface fuzzing by a gas flame. There is no black residue or uneven baking that occurs, and a smooth surface can be stably obtained by smooth finishing with a water-cooled roll. provide.

(Examples) Hereinafter, the details and examples of the method of the present invention will be further described.

As described above, the method of the present invention starts with a nonwoven fabric obtained by needle-punching a fiber web containing PPS fibers.

The basis weight of this fiber web is usually ² of 300 to 700 g / m, as the PPS fibers may be short fibers, also may be a long fiber, the fiber web structure in the fiber
Preferably, it is contained in an amount of 50% by weight or more.

Other fibers mixed with PPS fibers include known fibers such as aromatic polyamide fibers, aromatic polyester fibers, polyamide fibers, and polyester fibers, and one or more of these fibers may be mixed with PPS fibers as appropriate to form PPS fibers. Together with the fiber web.

The fiber web is then subjected to a heat treatment. In the present invention, indirect heating using an infrared heater is used as the heat treatment, and contact heating using a hot plate or the like is excluded. The indirect heating is not limited to heating by the infrared heater, and various means such as electric heating are possible, but the infrared heater is the most effective.

In the indirect heating treatment, it is necessary to melt-soften at least one nonwoven fabric on the surface of the nonwoven fabric containing the PPS fiber, and this results in a smooth state due to partial fusion to the surface together with subsequent pressing by a hot roll.

Therefore, at the time of the heat treatment, the degree of melt softening of the surface of the nonwoven fabric can be changed by the amount of heat received by the infrared ray, and the feed rate of the nonwoven fabric at the time of the heat treatment is appropriately controlled.

The hot press using a hot roll generally uses three known calender-type hot rolls.

The temperature of the hot roll may be any temperature suitable for crushing, and is usually around 175 ° C.

Indirect heating by an infrared heater is also performed by installing an infrared heater above the three calendars.

Thus, the non-woven fabric which has been subjected to heat treatment, hot-pressed by a hot roll, and processed on the surface is subsequently cooled through a water-cooled roll and finished to a smooth surface, and is known as a filter cloth material such as a bag filter. To form a back filter or the like.

Next, a case where a filter cloth of a bag filter is manufactured by the method of the present invention will be described.

Example 2 Using a fiber layer made of 100% PPS fiber (trade name: PROCON, manufactured by Toyobo Co., Ltd.) having a fiber length of 51 mm and a base cloth also made of 100% PPS filament (manufactured by Toyobo Co., Ltd.), the basis weight was 500 g / m2. The fiber web of No. ² was prepared, and needle punching was performed on the web to prepare a raw material of needle punched nonwoven fabric as a material.

Then, the nonwoven fabric was subjected to a surface treatment using a facility in which an infrared heater was installed on a three-calender, a hot roll facility and a water-cooled roll facility of the three calender.

The temperature of the hot roll in the three calenders was 175 ° C.

The speed at which the raw material is passed through the three calenders equipped with infrared heaters and the speed at which the raw material is passed through the heat roll equipment of the three calenders are controlled while observing the melting state of the surface, thereby changing the amount of heat received by the raw material from infrared rays. The variety of baking intensity was revealed.

FIGS. 1 and 2 are intermediate views of baking, and are microscopic photographs showing the surface state of the nonwoven fabric in the most standard surface processing in the present invention.
(2) shows a portion which is melted by heating and is fused and smoothed.

As is apparent from the figure, the surface of the nonwoven fabric has a partially smoothed portion due to fusion, and it is confirmed that the indirect heating by the infrared heater is effective when PPS fibers are included.

Next, as described above, the properties of the nonwoven fabric containing PPS fibers include an improvement in acid resistance. The following table shows the results of a comparison test with a nonwoven fabric made of other fibers.

 In addition, the test method was implemented according to the following.

(B) The sample is punched out in the vertical direction, 5cm x 20cm.

(B) Submerge the sample in 5% sulfuric acid (% by weight) for 5 minutes.

(C) Remove the sample and let it drop naturally for 30 seconds.

(D) Next, the sample is placed in a thermostat set at 150 ° C. and left for 1 hour.

(E) The above steps (b) to (d) are repeated five times, and then the sample is washed with water and dried, and the strength is measured to obtain the strength retention.

From the above table, it is proved that the PPS fiber nonwoven fabric has better acid resistance performance than other nonwoven fabrics.

(Effect of the Invention) As described above, the method of the present invention uses a nonwoven fabric containing PPS fibers as a material, partially heats and melts the surface by indirect heating using an infrared heater, and then presses with a hot roll, and then uses a water-cooled roll. This is a surface treatment of a non-woven fabric for filter cloth that cools to form a smooth surface.By using PPS fibers, it has the advantage of greatly improving the acid resistance compared to conventional polyester and aramid fibers, The surface treatment by indirect heating is adopted instead of the surface treatment by contact heating, and the surface smoothness by heating and fusing, which has been considered difficult in the past due to the high melt viscosity which is the characteristic of PPS fiber, is obtained. In addition, since the treatment is based on indirect heating, there is no black residue remaining due to gas flames or uneven baking, and a good surface condition over the entire surface By forming a state and cooling with a water-cooled roll, the filter cloth has a remarkable effect of improving the surface smoothness as a nonwoven fabric and improving the dust peeling performance during dust collection.

According to the second aspect of the present invention,
The surface can be widely changed and formed into a film-attached state by a porous state, and an effective nonwoven fabric for filter cloth suitable for the purpose and application can be manufactured.

[Brief description of the drawings]

1 and 2 are views showing the surface condition of a nonwoven fabric obtained by the surface processing method of the present invention.

Claims (2)

(57) [Claims] 1. A fiber web containing polyphenylene sulfide fibers is subjected to needle punching to form a formed nonwoven fabric, and the surface thereof is indirectly heated with an infrared heater to melt at least a part of the surface fibers. A method of processing the surface of a nonwoven fabric for a filter cloth, wherein the surface-melted fiber is crushed and fused by hot pressing in step (1), followed by cooling with a water-cooled roll to finish the surface in a smooth state. 2. The method according to claim 1, wherein the indirect heating by the infrared heater controls the intensity of radiant heat energy received by the nonwoven fabric, and melts a part of the nonwoven fabric surface from a state where a porous film is stuck on the surface. A method for surface-treating a nonwoven fabric for a filter cloth, characterized in that the surface is changed to a state in which the non-woven fabric is used.