JPH01306614A - Production of polyetherimide fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber, excellent in heat and chemical resistance and a suitable as a matrix for composite materials, by melting an aromatic polyetherimide and discharging the molten polyetherimide through a spinning nozzle for spinning at a specified linear velocity calculated from a sectional area of a discharging hole, a discharging amount per minute and a density. CONSTITUTION:A polyetherimide composed of a repeating unit with >=85mol% unit expressed by the formula is melted at 370 deg.C and extruded through a spin ning nozzle at 0.5-3.5m/min discharging linear velocity (V) calculated by formula V = Q/(AXdelta) using a sectional area (A) of a nozzle hole, a discharging amount per minute (Q) of the molten polyetherimide and a density (delta) and at 345-375 deg.C of the front face temperature of the spinning nozzle. The discharged polyetherimide is passed through a heating cylinder with 200-350 deg.C atmospheric temperature surrounding the spinning nozzle and extending downward to be spun. The spun yarn is then wound, thus obtaining the objective fiber consisting of a multi-filament yarn.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to polyetherimide, which is suitably used as a matrix for composite materials in which the matrix resin is reinforced with carbon fiber, aramid fiber, glass fiber, etc. This invention relates to a method for producing fibers.

(Prior art) When heat-resistant thermoplastic polymers such as polyether ether ketone (PEEK), polyether sulfone (PES), and polyphenylene sulfide (PPS) are used in the matrix of composite materials, thermosetting polymers are used in the matrix. A composite material with superior toughness, impact resistance, fatigue resistance, etc. can be obtained, and the molding time can be shortened. Therefore, in recent years, research on composite materials that use the above-mentioned thermoplastic polymer as a matrix has become active. 1986-25
As described in Japanese Patent No. 8017, attempts have been made to use PEEK in the form of multifilament yarns or fabrics that have drapability and are convenient for molding complex-shaped composite materials.

On the other hand, polyetherimide, which is amorphous and has the highest glass transition temperature, is also being used as a matrix for composite materials. However, polyetherimide has an extremely high melt viscosity, and the melt viscosity changes greatly depending on the temperature. It was difficult to spin the yarn in a stable state without yarn breakage.

[Problem to be solved by the invention]

The present invention was developed because conventionally, there was no known method for spinning polyetherimide multifilament yarn stably for a long period of time, and it was difficult to obtain polyetherimide fibers suitable for use in the matrix of composite materials. , was made to solve that problem.

That is, the present invention provides a method for producing polyetherimide fibers that can industrially stably obtain polyetherimide multifilament yarns that have excellent heat resistance and chemical resistance and are suitable for use in the matrix of composite materials. do.

[Means to solve the problem]

The present invention was developed as a result of repeated research by the inventors on melt spinning of polyetherimide.The conditions around the spinneret are significantly related to the spinning condition, and in particular, the linear velocity of the molten polymer discharged from the spinneret, This was done based on the discovery that the temperature at the front surface of the spinneret and the ambient temperature immediately after exiting the spinneret are important for stable spinning without yarn breakage over a long period of time.

That is, the present invention provides a method for obtaining a multifilament yarn by melting polyetherimide, in which 85 mol% or more of the repeating units are units represented by , the linear velocity ■ of the molten polyetherimide discharged from the spinneret is 0.5 to 3.
5 m7 minutes, spinneret front temperature 345-375℃,
An atmosphere heating tube that surrounds the spinneret and extends downward is provided, and the atmosphere temperature inside the heating tube is 200 to 350.
The present invention provides a method for producing polyetherimide fibers characterized by satisfying the conditions of °C.

In the present invention, the polyetherimide may contain less than 15 mol% of copolymers, blends, or inorganic additives. In order to melt and extrude such polyetherimide from a spinneret, Melt temperature 35
Preferably from 0 to 380°C, the melting temperature is 350°C
If the temperature is less than 'C', the viscosity of the molten polymer is extremely high, 10,000 poise or more at a shear rate of 300 sec-' using a flow tester, and the distribution of the molten polymer flow within the spinning puncture becomes very poor, making it unstable. It becomes difficult to spin the product. On the other hand, when the melting temperature exceeds 380°C, gas is generated due to decomposition of the polymer and the oligomers contained therein and also due to moisture, making stable spinning difficult.

It is necessary to extrude the polyetherimide melted at the above-mentioned appropriate temperature from the spinneret at a low linear velocity (1) of 0.5 to 3.5 m/min, preferably 0.7 to 2.5 m/min. Although the details of the reason for this are not yet clear, one factor is that polyetherimide melted at a temperature in the range where no gas is generated still has too high a viscosity, which causes It is conceivable that the movement of the fluid in the part) is extremely unstable.

Therefore, if the linear velocity of discharge ■ is faster than 3.5 m1 minute, a constant flow will not be formed in the land area, stable discharge will not be performed, and a stable spinning state will not be obtained. Therefore, if the discharge linear velocity (■) is less than 0.5 m1 min, even if a constant flow is formed at the land, the spinning tension at an extremely high draw ratio will be applied to the discharged material and its separation from the spinneret. Therefore, yarn breakage is likely to occur, making it difficult to obtain a stable spinning state.Setting the discharge linear velocity V to such a low speed is extremely unique from the perspective of conventional melt spinning. That is, for ordinary melt-spun polymers such as polyethylene terephthalate, ■ is usually 10 to 15 Il.
It takes about 1 minute. Further, even in polymers with a high degree of polymerization such as those used in fibers for industrial use, the time period (■) is about 4 to B-7 minutes.

Furthermore, it is necessary to maintain the front temperature of the spinneret from which the polyetherimide is discharged at 345-375°C. If this temperature is lower than 345° C., the elongation and thinning of the discharged polymer will not be carried out smoothly, and thread breakage will increase.

On the other hand, if the temperature exceeds 375° C., a large amount of foreign matter will adhere to the spinneret surface, making it impossible to stably spin for a long period of time.

Maintaining the spinneret surface temperature within the above-mentioned range can be accomplished by controlling the temperature around the spinneret and the temperature of the atmosphere immediately below the spinneret.

In order to control the atmospheric temperature immediately below the spinneret and to ensure stable collection of the polymer discharged from the spinneret, an atmosphere heating tube surrounding the spinneret and extending downward is provided; It is also necessary to maintain the atmospheric temperature within the heating cylinder at 200 to 350'C. The direct reason for providing the atmosphere heating cylinder is to prevent the molten polymer discharged from the spinneret from being cooled rapidly. That is, without this heating cylinder, the ambient temperature below the spinneret would be significantly lower than the high temperature, high viscosity molten polymer discharged, so the polymer would be rapidly cooled and the spun yarn would be wound at high speed. I won't be able to do that. This is particularly noticeable in polyetherimide, where the linear velocity V discharged from the spinneret must be slowed down as described above, and the single fiber denier, which is preferably used in the matrix of the composite material without an atmosphere heating tube, is 20 de Since it is not possible to obtain an ungrooved polyetherimide multifilament yarn, the atmosphere heating cylinder is preferably cylindrical in order to maintain the atmospheric temperature inside the cylinder as uniform as possible, and its length is within the range from the front of the spinneret. 30-10
A relatively small device of about 0 ell can sufficiently achieve the purpose. Even if an atmosphere heating cylinder is provided, if the atmosphere (usually air) temperature below the spinneret near the spinneret in the cylinder is less than 200°C, the front temperature of the spinneret will be 345°C.
℃ or the discharged polyetherimide cools down rapidly, resulting in many thread breakages and making it impossible to stably take off the polyetherimide fibers (on the contrary, if the atmospheric temperature exceeds 350℃ In such cases, the temperature at the front surface of the spinneret may exceed 375°C, or the temperature of the discharged polyetherimide may rise midway through the process without being properly cooled. Polyetherimide fibers cannot be drawn out stably over time.

By satisfying the above conditions, the polyetherimide fiber discharged from the spinneret has a length of 100 to 500 m.
It can be wound up at a speed of 1 minute, preferably 150 to 400 m/min. When winding, it is recommended to apply water or oil to the polyetherimide fibers when the polyetherimide is cooled and solidified.If the winding speed is less than 100-7 minutes, not only will productivity be low, but the composite The strength of the polyetherimide fiber suitably used in the matrix of the material is 1.5 da or more and the elongation at break is 20.
It becomes difficult to obtain a multifilament yarn of 0% or less without a so-called drawing process. On the other hand, if the winding speed is 50
If it exceeds 0 + i/min, thread breakage will occur.

The composite matrix has a single fiber denier of 20d.
less than e, the number of filaments is 10 or more, and the strength is 1.5
A polyetherimide multifilament yarn having a breaking elongation of 200% or less with a g/de or more is preferably used.

In order to obtain such a multifilament yarn, it is necessary to have 10 or more discharge holes so that the cross-sectional area of the land portion of each discharge hole is 20 de undropped single fiber from the ratio of the above-mentioned discharge linear velocity (■) and winding speed. Polyetherimide can be melt-spun as described above using a spinneret with an area that gives a denier and a corresponding linear discharge speed and winding speed. Because of the poor quality, the improvement in mechanical properties is not so great even after drawing heat treatment.
Made of 0de ungrooved filament and has a strength of 1.5
A so-called undrawn multifilament yarn having an elongation of at least de and no more than 200% is sufficient.

However, for uses other than matrices, or even for matrices, for example, when yarn is wound around to form a matrix, polyetherimide yarn with a lower elongation may be required, so it is recommended to use a polyetherimide yarn with a lower elongation. Multifilament yarns can be used for drawing heat treatment, which is carried out in the same way as in the case of ordinary thermoplastic fibers, by the so-called direct drawing carried out after the yarn is cooled and solidified after exiting the spinneret, or by the so-called direct drawing carried out after the undrawn yarn is once wound up. Any method described separately may be used.

To explain the conditions for polyetherimide multifilament yarns that are preferably used in the matrix of composite materials, if the denier of the single fiber exceeds 20 de, a fabric with excellent drapability that facilitates the molding of composite materials of complex shapes will be produced. 20d is difficult to obtain, and if it is thinner than 4d, thread breakage will easily occur during spinning and subsequent weaving processes.
e or less, particularly preferably 4 de or more and 15 de or less, and the number of constituent filaments is preferably 10 or more, especially 20 or more, from the viewpoint of productivity of threads and matrix fabrics, and the breaking strength and elongation are in accordance with the processability into fabrics. In terms of the stability of the dimensions and form of the obtained fabric, the strength should be 1.5 g/de or more, especially 1.5 g/de or more.
It is preferable that the elongation is 8 g/de or more and the elongation is 200% or less, especially 150% or less.

[For production]

According to the production method of the present invention described above, polyetherimide, which has a narrow temperature range in which a stable melting state can be obtained and an extremely high melt viscosity, makes it difficult to obtain fibers with a diameter of 20 de or less. Spun in an extremely stable state without yarn breakage over time, with a strength of 1.5 g/de or more and an elongation consisting of filaments of 20 de or less, which are excellent in heat resistance and flame retardancy, and are suitable for use in the matrix of composite materials. It is possible to obtain multifilament yarn with a high productivity of 200% or less.

〔Example〕

The present invention will be further explained below with reference to Examples and Comparative Examples.

Polyetherimide (Ultsum #1000 manufactured by CUE)
) chips were dried in a hot air dryer at 180°C for 4 hours. This chip was melted at 370'', extruded through a spinneret with 36 holes at a rate of 13 g per minute, and wound at a speed of 250 va/min. Grant 450 de/
A 36 fil multifilament yarn was obtained. In this case, spinnerets with different discharge hole sizes are used,
The temperature in front of the spinneret and the ambient temperature immediately below the spinneret in the atmosphere heating cylinder were also varied. Table 1 shows the discharge hole dimensions of the spinneret, the linear velocity V of the molten polymer discharged from different spinnerets, the front temperature of the spinneret, and the ambient temperature in the atmosphere heating cylinder, and Table 2 shows the The maximum stress of multifilament yarn and the elongation and spinning tension that give it are shown.

Table 2 Note that ■ in Table 1 indicates that the discharge amount Q is 13 g/min, the cross-sectional area A of the discharge hole is 36 x π x (hole diameter) 214, and δ
The maximum stress and corresponding elongation in Table 2 are determined from V = Q / (A x δ) with 1.17.
01° This is the value read from the stress-elongation curve obtained under the conditions of a tensile speed of 200 m/min. In addition, the spinning condition is 0 to 1 yarn breakage in 2 hours of continuous operation, Δ to 012 to 3 yarn breakages,
4 or more times was marked as x. Difficulty in winding the spinning condition occurs when winding cannot be continued and therefore the number of yarn breakages cannot be determined.

In the case of Examples 1 to 4, which are implementations of the method of the present invention, the second
As shown in the table, polyetherimide multifilament yarn with excellent mechanical properties could be stably spun for a long time with little yarn breakage, whereas Comparative Example 1 had a V of 9.
Even though it is an appropriate value for ordinary melt-spinning polymers such as polyethylene terephthalate, which is 8 or 7 minutes, it is too large for polyetherimide and difficult to wind. Although the value of .4 m7 minutes is the lower limit adopted for spinning polyethylene terephthalate, it was still too large for polyetherimide, and yarn breakage occurred frequently, making stable spinning impossible. In the case of Comparative Example 3, on the contrary, V was too small and the spinning draft became large, resulting in frequent yarn breakage. In the case of Comparative Example 4, the temperature at the front surface of the spinneret and the temperature of the atmosphere below it were too low to allow stable spinning, and the mechanical properties of the obtained yarn were also insufficient. On the other hand, in the case of Comparative Example 5, the temperature at the front surface of the spinneret and the temperature at the lower atmosphere were too high, and a large amount of foreign matter accumulated on the front surface of the spinneret, making it impossible to perform stable spinning for a long time.

In addition, as Example 5, when the multifilament yarn obtained in Example 3 was stretched 1.2 times between rollers heated to a surface temperature of 200°C, the strength was 2.6 g/de and the elongation was 40%. We were able to stably obtain multifilament yarn.

〔Effect of the invention〕

According to the method of the present invention, the filament is made of a filament having a fiber denier of less than 20 de, which has excellent heat resistance and chemical resistance, and is suitably used as a matrix of a composite material, and has a strength of 1.
The effect is that polyetherimide multifilament yarn having a breaking elongation of 5 g/de or more and a breaking elongation of 200% or less can be stably obtained industrially.

It goes without saying that the polyetherimide fiber obtained by the method of the present invention can be used not only for the matrix of composite materials, but also for applications that utilize the fiber form.

Claims (1)

[Claims] A method for obtaining a multifilament yarn by melting polyetherimide, in which 85 mol% or more of the repeating units are units represented by ▲ mathematical formula, chemical formula, table, etc. ▼ and extruding it from a spinneret and winding it up. , the molten polyetherimide discharged from the spinneret is calculated by V = Q / (A × δ), where the discharge hole cross-sectional area of the spinneret is A, the discharge rate of molten polyetherimide per minute is Q, and the density is δ. Linear velocity V is 0.5 to 3.5m
/min, the temperature at the front surface of the spinneret is 345 to 375°C, and an atmosphere heating cylinder that surrounds the spinneret and extends downward is provided, and the atmosphere temperature inside the heating cylinder is 200 to 350°C. A method for producing polyetherimide fiber characterized by: