JPH07145542A - Production of melt blown nonwoven fabric of polyamide - Google Patents

Abstract

PURPOSE:To provide a production method for melt blown nonwoven fabric of polyamide, capable of producing ultra-fine yarn nonwoven fabric of polyamide having uniform weight and extremely excellent flexibility free from occurrence of polymer spherules even when increased of a delivery amount of a single hole to >=0.25g/minute at high productivity stably for many hours. CONSTITUTION:A melt blown nozzle die which does not substantially has a flat part at the end of a vertical angle, a distance L of the end of the vertical angle projected outward from a lip end of >=0mm and <=0.8mm, a lip interval W of >=1.0mm and <=2.0mm and the vertical angle theta of the isosceles triangle of >=80 deg. and <=100 deg. is used, the melt viscosity of a fiber-forming polyamide in passing an orifice nozzle is >=20 poise and <=250 poise and jetting pressure of a high-temperature high-speed gas is >=0.2kg/cm<2> and <=1.0kg/cm<2> to provide a production method for melt blown nonwoven fabric of polyamide.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is capable of stably producing a polyamide meltblown fiber nonwoven fabric with a high productivity, with little mixing of polymer beads, which is a drawback of the meltblown nonwoven fabric, and having a texture having excellent basis weight uniformity and flexibility. It is about the method.

[0002]

2. Description of the Related Art A method for producing a non-woven fabric by melt-spinning a thermoplastic resin, making it into a fiber stream by a high-speed gas, and then collecting it in a sheet form, is disclosed in JP-A-49-10258. Various proposals have been made in JP-A-49-48921, JP-A-50-121570 and the like called the melt blown method, and a method for forming a fiber-forming polyamide into a nonwoven fabric by the melt blown method is also disclosed in JP-B-60-22100. JP-B No. 60-56825, JP-A No. 50-121570, JP-A No. 55-90663, JP-A No. 50-46972, JP-A No. 54-134177, and JP-A No. 55-55. -90663 is proposed.

Of these, Japanese Patent Laid-Open No. 55-90663 discloses that a molten polyamide is discharged from a die nose having an isosceles triangular cross section and having a large number of die orifices at the tip of the die, and the vicinity of the open end of the die orifice. In the melt-blown method of thinning the polyamide by injecting heated gas to, the width of the flat portion of the tip of the dynos is 0.1.
~ 0.2mm, heating gas temperature 320 ~ 370 ℃, heating gas pressure
1.5 to 6.0 kg / cm ² , heating gas jet slit width 0.10 to
0.20 mm, the protruding distance of the tip of the dynose from the tip of the lip plate is 0.01 to 0.40 mm, the apex angle of the isosceles triangle is 40 to 90
It is proposed to be °.

Further, the inventors of the present invention have disclosed in JP-A-3-146756 that the fiber-forming polyamide having a relative viscosity of 1.6 to 2.2 poise has a melt viscosity of 20 to 250 poise at the nozzle orifice portion and a nozzle temperature of 270 to 320. It proposes a method for producing a polyamide meltblown non-woven fabric having a good basis weight uniformity and an extremely soft texture by setting the temperature to ℃.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention JP-A-55-90663
In the production of the polyamide meltblown nonwoven fabric described in Japanese Patent Laid-Open No. 3-146756 and Japanese Unexamined Patent Publication No. 3-146756, a polyamide ultrafine fiber nonwoven fabric can be stably produced for a long time without generating polymer beads. However, the conventional method can be stably manufactured in a range where the single hole discharge rate is relatively small. For example, according to the method disclosed in JP-A-55-90663, the single hole discharge rate is 0.2 g / min or less. Even with the method disclosed in Kaihei 3-146756, the melt blown can be stably performed for a long time only when the single hole discharge rate is 0.25 g / min or less. That is, if the single hole discharge amount is made larger than these values in an attempt to increase the production amount, stains are attached to the periphery of the nozzle orifice and the lip end within a relatively short time, and the discharge of polyamide and the flow of hot air are disturbed. Melt blown cannot be continued due to the occurrence of balls and abnormal yarn breakage.

According to the present invention, even if the single-hole discharge rate is increased to 0.25 g / min or more, polymer beads are not generated, and a polyamide ultrafine fiber non-woven fabric excellent in uniformity of basis weight and excellent in flexibility is produced with high productivity. It is an object of the present invention to provide a method that can be manufactured in a time stable manner.

[0007]

According to the present invention, the cross section is an isosceles triangle, and the fiber-forming polyamide is melted and discharged from an orifice-shaped nozzle formed in a row at the apex angle end of the isosceles triangle. A pair of lips having a constant gap is provided on both sides of the isosceles side, and the high temperature and high speed gas jetted from the lip gap thins the fiber-forming polyamide into fine fibers, which are then collected in a sheet form. In the method for producing a polyamide meltblown nonwoven fabric, the apex end does not substantially have a flat portion, and the apex distance (L) of the apex end protruding beyond the lip end is 0 mm or more and 0.8 mm.
In the following, a melt blown nozzle die in which the lip interval (W) is 1.0 mm or more and 2.0 mm or less and the apex angle (θ) of the isosceles triangle is 80 ° or more and 100 ° or less is used. The melt viscosity when passing through the orifice nozzle
20 poise or more, and 250 poise, and the injection pressure of the hot high-velocity gas 0.2 kg / cm ² or more, a method for producing a polyamide meltblown nonwoven fabric, which comprises a 1.0 kg / cm ^2.

[0008]

The present invention will be described in detail below with reference to the drawings. The fiber-forming polyamide referred to in the present invention means, for example, nylon 6, nylon 6,6, nylon 7, nylon 11, nylon 12, nylon 6,10, polyhexamethylene isophthalamide, polyhexamethylene terephthalamide, polyparaxylene dodecane. An amide or an arbitrary polyamide having a fiber-forming property such as a copolymer thereof, and further a heat stabilizer, a light stabilizer, a pigment or a master batch prepared by dispersing a pigment in a thermoplastic polymer in advance or improving spinnability, , An additive for spinning the stickiness of the fiber, for example, an additive containing a known additive such as titanium oxide. Of these polyamides, nylon 6 and nylon 6,6 are particularly preferable in the present invention.

FIG. 1 is a sectional view of a melt blown nozzle used in the present invention. In a meltblown nozzle whose cross section is an isosceles triangle used in the present invention, it is important that the apex end does not have a substantially flat portion. When a flat portion is formed at the apex end as shown in FIG. 2, the high-temperature high-speed gas flow injected through the pair of lip intervals is flattened with the extension line of the isosceles side indicated by the broken line in the figure. Since it does not flow directly to the triangular part formed by the part, it becomes a state close to a vacuum, so the gas flow lacks stability, and the polymer of high temperature high speed gas flow in the orifice nozzle part where the polyamide polymer flow is discharged It is likely that the polymer balls, that is, the defects resulting from insufficient thinning of the polymer stream, are likely to occur, probably because the jetting into the stream and the thinning action also become unstable. In particular, when the single-hole discharge amount of the polymer is increased to exceed 0.25 g / min, the generation of polymer beads cannot be eliminated. On the other hand, when the apex portion does not have a substantially flat portion, there is no such problem. The phrase "the apex portion does not substantially have a flat portion" means that there is no flat portion, or if there is a flat portion, the width thereof is about 0.05 to 0.08 mm or less.

Further, in the melt blown nozzle die used in the present invention, it is important that the protrusion distance (L) at which the apex end protrudes outward from the lip end is 0 mm or more and 8 mm or less. That is, as shown in FIG. 2, when the apex end is on the inside without protruding outward from the lip end,
That is, when (L) is less than 0 mm, it becomes substantially impossible to clean the apex angle portion, which is the tip portion of the nozzle die, and it cannot be used for operation. Because, in the meltblown of polyamide, volatile substances such as oligomers and monomers that are present in a trace amount in the polyamide polymer cannot adhere to and accumulate around the apex when long-term operation is not possible. Need to be cleaned. A more urgent problem than this is that when the nozzle die is newly set and the molten polymer is discharged from the nozzle orifice for the first time, the deteriorated polyamide polymer that had been generated while the machine was stopped became unstable and Since it will become dirty, stable operation cannot be performed unless the main operation is started after cleaning and removing it cleanly, but such cleaning cannot be performed. On the other hand, if (L) becomes larger than 0.8 mm, the distance at which the high-temperature and high-velocity gas flow for thinning the polyamide polymer flow into the polymer flow after injection through the lip gap becomes large. Perhaps because of the expansion, the thinning fiber-forming action is significantly reduced, resulting in extremely poor thinning.

Furthermore, it is important that the lip gap (W) of the melt blown die used in the present invention is 1.0 mm or more and 2.0 mm or less. That is, the lip gap (W) is
If it is less than 1.0 mm, it becomes practically impossible to keep the lip gap constant over a width of more than 1.5 m and 2 m like a melt-blown die for operation. No matter how accurately the adjustment is made in advance, there are inevitable errors caused by thermal expansion of the material and deformation and distortion caused by repeated use of the nozzle die and lip, but the lip interval is less than 1 mm. If it is made smaller, the error becomes relatively large, and the high-temperature and high-speed substrate flowing and flowing therethrough produces flow rate and flow velocity unevenness in the die width direction according to this relative error, so stable melt blowing cannot be performed. . As a result, the fiber diameter and the basis weight are uneven in the width direction. Furthermore, if the lip gap is as small as 1 mm, a small amount of volatile substances such as oligomers present in the polyamide polymer will easily adhere and accumulate on the lip end when operating continuously for a long time, which causes a high temperature and high speed gas flow. Disturb or
Since the flow of the discharged polymer is disturbed, polymer beads are easily generated. In particular, this tendency becomes remarkable when the discharge amount of the polymer is more than 0.25 g / min.
On the other hand, when the lip gap exceeds 2.0 mm, the flow path of high-temperature and high-speed gas widens, so the minimum injection pressure of 0.2 kg required to sufficiently thin the polyamide polymer flow into fibers.
The amount of the gas for obtaining / cm ² is so large that it is wasteful, and at the same time, it causes poor thinning.

In the melt blown nozzle die used in the present invention, the apex angle (θ) of the isosceles triangle is 80 ° or more,
It is important that the angle is 100 ° or less. The vertical angle is less than 80 °,
Or, if it is larger than 100 °, the injection pressure of the high-temperature high-speed gas stream is 0.2 kg / cm, which allows the polyamide polymer flow to be finely fibrillated well when the single-hole discharge rate of the polyamide polymer is 0.25 g / min or more. Polymer balls will be generated before setting it to ² or more. The reason for this is not clear, but the high-temperature and high-velocity gas streams ejected from the pair of lip gaps have different apex angles.
It acts on the discharged polyamide polymer at an angle of 1/2 of (θ), but when the angle is 45 °, that is, when the apex angle is 90 °, the force of the gas flow causes It is presumed that the gas flow most efficiently suppresses the polymer flow because the components in the discharge direction and the component in the drag force direction orthogonal to the discharge direction are equal to each other, and flows downward, so that the fibers are most efficiently thinned. On the other hand, if the vertical angle becomes smaller,
Although the lower component of the force of the gas flow becomes large, the vertical drag component that gives the traction force to the polyamide polymer flow becomes small, so that the polyamide polymer flow cannot be sufficiently drawn, and as a result, thinning failure occurs Is considered to cause On the contrary, when the apex angle becomes large, the vertical drag component to the polyamide polymer flow becomes large, but the lower component becomes small, so that the polyamide polymer flow cannot be sufficiently pulled as a result, resulting in poor thinning. It is thought to cause a profit.

Further, in the present invention, the melt viscosity of polyamide when passing through an orifice nozzle is 20 poise or more,
It is important to keep it below 250 poise. That is, the melt viscosity of the polyamide at the time of passing through the orifice nozzle, that is, the melt viscosity of the polyamide at the time of melt blown has a very large influence on the melt blown tone. When the melt viscosity in the spinneret part is less than 20 poise, the melt tension of the polymer becomes too small, the fiber-forming property is lowered, the polymer stream is severely cut, and the length of the formed fiber becomes short. As a result, the entanglement between the fibers is reduced and the fiber strength is also reduced, so that they are not normally collected and are scattered like cotton in the air.
There are many things that can be called, and it becomes virtually impossible to continue stable melt blown. Further, the obtained meltblown non-woven fabric also has a large amount of streak-like or string-like fiber bundles, resulting in a poor basis weight uniformity and appearance.
On the other hand, when the melt viscosity of the polyamide when passing through the orifice-shaped nozzle exceeds 250 poise and becomes large, firstly, it becomes difficult to progress the thinning by melt blown. That is, it is necessary to increase the high-temperature and high-speed gas flow rate and the temperature thereof to increase the thinning, which is disadvantageous in terms of energy consumption.

[0014] In the present invention the injection pressure of the hot high-velocity gas 0.2 kg / cm ² or more, it is important to 1.0 kg / cm ² or less. Injection pressure of high-temperature and high-speed gas is 0.2 kg / cm ²
When it is less than 1, when the single-hole discharge amount of the polyamide polymer to be melt-discharged is 0.25 g / min or more, it is not possible to sufficiently thin the fibers, and the obtained polyamide melt-blown nonwoven fabric contains polymer balls, Moreover, the meltblown nonwoven fabric is coarse and hard and has a poor texture.
On the other hand, when the jetting pressure of the gas at high temperature and high speed is higher than 1.0 kg / cm ² , when the melt blown is carried out for a long time, colored deposits are accumulated around the lip and the orifice nozzle. This buildup builds up over time and eventually contacts the extruded polymer stream. In that case, defective yarn breakage occurs on the surface of the spinneret.

Generally, in meltblown, the fibers formed are not completely continuous but are assumed to be discontinuous fibers having a finite length. This means that in meltblown, the polymer flow after thinning is It can cut regularly and stably without being able to follow the high-speed deformation. On the other hand, the above-mentioned defective yarn breakage is completely different from that described above, and since it is cut before thinning, it is of course unstretched and extremely thick. is there. Although the exact reason for the formation of these deposits is not known, in meltblown, where the melt viscosity is too high, the factors that make the polymer stream thin by the high-temperature and high-speed gas become irregular, and the cutting also occurs irregularly. It is presumed that a part of it scatters in directions other than the normal blown direction and adheres to the periphery of the spinneret.

The melt-blown non-woven fabric produced by the method of the present invention preferably has a fiber diameter of 5 μm or less, but as described above, according to the method of the present invention, the fiber diameter is 5 μm. In the following, it is possible to stably produce a polyamide meltblown nonwoven fabric having a high basis weight uniformity and an extremely soft texture with high productivity. Furthermore, the basis weight of the meltblown nonwoven fabric produced by the method of the present invention is generally in the range of 5 to 200 g / m ² , although it depends on the intended use. For example, when using it for adhesive interlining, use a low basis weight with a surgical gown, drape,
When it is used for sterilization wraps, batting for clothing, etc., it is used for medium weight, and when it is used for agriculture, civil engineering, and industry, it is used for medium weight or high weight.

The following are examples of industrial applications using the nonwoven fabric of the present invention.・ Building materials Waterproof materials such as asphalt roofing base cloth or coating film waterproof layer reinforcing cloth, dew condensation prevention sheet, house wrap base cloth, heat insulating glass wool skin material, adsorption sheet,
Thermal insulation sheet-Agricultural material Light-shielding sheet, seedling-raising sheet, drainage sheet, root-prevention sheet, weed-proof sheet-Household materials Furoshiki, handbag, disposable body warmer bag, curtain, shoji paper, furniture, chair lining, insect repellent sheet , Base fabric for tufted carpets, work clothes, simple disposable clothing, heat insulation batting, batting prevention sheet for batting, quilting sheet, wiping cloth, leather base cloth, shoe interior material, tape, interlining, industrial materials Air filter, oil filter, wire holding tape, packing material, insulating tape, battery separator, FRP base cloth, vehicle materials (car mats, car seats, etc.)-Medical / sanitary materials Paper diapers, medical gowns, surgical cloth, patches Base cloth, napkin

[0018]

EXAMPLES The embodiments of the present invention will now be described with reference to specific examples, but the present invention is not limited to these examples. The polyamide of the present invention has a relative viscosity of 98% H ₂ SO.
A solution of ₄ in a solvent containing 1 g / 100 cc of polyamide was measured at a temperature of 25 ° C. using a capillary viscometer. Also,
The average diameter of the fibers constituting the meltblown nonwoven fabric obtained by the method of the present invention was determined by taking a photograph of the meltblown nonwoven fabric magnified 1000 times with a scanning electron microscope, measuring the diameter of 100 fibers, and averaging the numbers.

Examples 1 to 5 and Comparative Examples 1 to 9 Orifice nozzles having a hole diameter of 0.3 mm as shown in FIG.
Using a meltblown device equipped with a meltblown nozzle die having a die width of 2100 mm arranged in a row at 0.75 mm pitch, using a nylon 6 having a relative viscosity of 2.01 as a raw material polymer, a polymer melting temperature of 290 ° C. (However, in Example 8, 330 ° C., 260 ° C. in Example 9), hot air of 290 ° C. was used as a high-temperature and high-speed gas, and a polyamide meltblown nonwoven fabric was produced under the other main meltblown conditions shown in Table 1. The evaluation results are shown in Table 2.

[0020]

[Table 1] Projection distance (L):-indicates a state of being retracted inward.

[0021]

[Table 2]

In Examples 1 to 5, which are examples of the present invention,
A melt blown non-woven fabric having good melt blown process condition and melt blown non-woven fabric quality was obtained even at a high single jetting amount of about 0.6 g / min. On the other hand, in Comparative Examples 1 to 9 which are outside the present invention, in any of the examples, the melt blown process tone and the quality of the melt blown nonwoven fabric are poor even at a low discharge amount of about 0.3 g / min for a single hole, High productivity was not obtained.

[0023]

EFFECTS OF THE INVENTION According to the present invention, a polyamide meltblown non-woven fabric having a good basis weight uniformity which has been conventionally obtained only with a low productivity, and which has almost no soft polymer blend which is a defect of the meltblown non-woven fabric, has a very soft texture. Can be manufactured with high productivity. The obtained polyamide meltblown nonwoven fabric can be suitably used as an interlining material for clothing, a gown for medical use, a drape, a sterilizing lap, a quilted batting, and the like. In addition, even with a low basis weight, it has good uniformity of basis weight, so even with a low basis weight, it has the effect of preventing strike-through of the adhesive resin on the adhesive interlining and the prevention of bacteria and the like, and is flexible, breathable and breathable. Excellent in.

[Brief description of drawings]

FIG. 1 is a sectional view of a melt blown nozzle used in the present invention.

FIG. 2 is a cross-sectional view of a conventional meltblown nozzle.

[Simple explanation of symbols]

 L: Projection distance from the lip end of the apex angle W: Lip gap θ: Die apex angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location D04H 3/03 A 7199-3B

Claims (1)

[Claims] 1. A fiber-forming polyamide is melt-discharged from an orifice-shaped nozzle having a cross-section of an isosceles triangle, which is formed in a row at the apex angle end of the isosceles triangle, and a constant gap is formed on both sides of the isosceles triangle. In a method for producing a polyamide meltblown nonwoven fabric, which comprises providing a pair of lips having the above, and thinning the fiber-forming polyamide into fine fibers by a high-temperature and high-speed gas ejected from the lip gap, and then collecting the fibers into a sheet. , The apex angle end portion does not have a substantially flat portion, and the protrusion distance (L) of the apex angle end portion protruding outward from the lip end is 0 mm or more and 0.8 mm or less, the lip interval (W)
Is 1.0 mm or more and 2.0 mm or less, and the apex angle of the isosceles triangle
(θ) 80 ° or more, using a melt blown nozzle die of 100 ° or less, the melt viscosity when passing through the orifice nozzle of the fiber-forming polyamide 20 poise or more, 250 poise or less, and of the high-temperature high-speed gas Injection pressure 0.2kg
/ Cm ² or more, the production method of the polyamide meltblown nonwoven fabric, which comprises a 1.0 kg / cm ^2.