JPS6163704A - Method of spinning low-molecular weight polymer - Google Patents

Abstract

PURPOSE:To improve spinnability of a low-molecular weight polymer which is observed to have stringiness but has poor spinning properties, by using a nozzle plate having extrusion holes with peripheral channels around the holes, respectively, in spinning the polymer. CONSTITUTION:A low-molecular weight polymer which is obserbed to have stringiness but has poor spinning properties is spun by using the nozzle plate 1 having a desired number of the extrusion holes 2 which is provided with the bored peripheral channels 3 at fixed intervals round the holes. A ratio of the depth C of the peripheral channels 3 to the height H of peripheral bank H carved between the extrusion holes 2 and the peripheral channels 3 is preferably 0.02-1.5.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for spinning low molecular weight polymers, and more specifically, a method for spinning low molecular weight polymers that exhibit spinnability but poor spinnability. The object of the present invention is to provide a spinning method that improves properties.

(Conventional technology 2 Problems to be solved by the invention) It goes without saying that advances in science and technology have created fiber-shaped products from various fiber-forming substances and have greatly contributed to the improvement of living culture. In addition, new and high performance,
At present, the demand for highly functional fiber materials is unmet.゛Pitch-based carbon fiber, pitch-based and phenolic resin-based activated carbon fiber, and metal polymer-based new material.
- Ceramic fibers can be obtained as final fibers with high performance, but although the spinnability of these raw materials as fiber-forming substances is recognized to a certain extent, it is not economical to perform spinning using conventional techniques. There are still many substances with which it is difficult to obtain suitable spinning results. These fiber formation advantages include (1) low degree of polymerization, (2) low melt viscosity, low i31 Troughton viscosity, (4) high apparent combing activation energy, and/or (5) spinning nozzle material. It has significant wetting properties, which are negative characteristics for fiber formation. For example, various spinning pitches, various organometallic polymers (polycarposilan,
polysilazane, polyaluminoxane, etc.).

Various low polymerization degree organic and inorganic polymers.

If these materials are spun using conventional techniques, spinnability is poor and specific problems in spinning operation include (a) yarn breakage, (b) uneven fineness, and (c) clogging of discharge holes in severe cases. This has made it extremely difficult to carry out spinning operations that meet industrial economics.

(Means for Solving the Problems) The present inventors have made extensive efforts to develop a spinning method for suitably spinning a fiber-forming substance, that is, a low molecular weight polymer, which has poor spinnability but poor spinnability. As a result of research, Japanese Utility Model Publication No. 35-12911 proposed a spinning nozzle plate with grooves for the purpose of smooth cleaning, that is, a spinning nozzle plate with grooves around the discharge hole. However, since the present invention has a purpose different from that of the known nozzle plate, the structure of the spinning nozzle plate has been devised and improved to achieve an effect that meets the purpose. Although the details of the reasons for this are not clear, the present invention was achieved by discovering that significantly more favorable spinning properties and spinning operability can be obtained compared to the use of conventional methods.

That is, in the present invention, the circumferential grooves at predetermined intervals around the hole are
This is a low molecular weight polymer spinning method that solves the problem by using a nozzle plate with a desired number of discharge holes cut out for each return during spinning.

The nozzle plate used in the present invention is made of a material in which a desired number of discharge holes can be drilled, and zero circumferential grooves can be cut at predetermined intervals around the holes for each response.

There are no particular limitations on the material as long as it has sufficient mechanical strength to withstand various operations related to spinning.

Examples include various metal alloys, metal sintered bodies, fine ceramic sintered bodies, glass, etc., but of course, the chemical properties of the fiber-forming substance to be used should be taken into account and a material suitable for the substance should be selected. Needless to say, it is necessary.

The fiber-forming substances to which the method of the present invention can be applied are as follows.

For the formation of the above-mentioned fibers, various spinning pitches with negative properties, various organometallic polymers (polycarpodilane, polysilasane, polyaluminoxane), various low polymerization degree organic and inorganic polymers, etc. can be used. but,
It is not limited to these.

The spinning nozzle plate used in the present invention will be explained in detail below with reference to the drawings. FIG. 1 is a plan view of one embodiment of the nozzle plate 1, FIG. 2 is an enlarged plan view of one of the discharge holes 2 and its surroundings, and FIG. 3 is an enlarged plan view of one of the discharge holes 2 and the fourth
The figure is an enlarged vertical cross-sectional view of a main part of a typical conventional discharge hole for comparison, showing the structure of each.

Although FIG. 1 shows a nozzle plate 1 in which two circular discharge holes 2 are arranged concentrically, this form is not necessarily a necessary condition for the nozzle plate 1 to carry out the method of the present invention. The number of discharge holes 2 to be drilled in the fiber can be arbitrarily selected depending on the type of collection of fibers to be produced. Further, the diameter of the discharge holes 2 can be arbitrarily selected depending on the characteristics of the fiber-forming substance used and the spinning conditions. Note that the cross-sectional shape of the discharge hole 2 may be a circle, trilobal, cross, etc., but is not limited to these (the important thing here is that the shape of the groove bank 4 between the discharge hole 2 and the circumferential groove 3 Width A
9 Width B of the circumferential groove 3, depth C of the circumferential groove 3 from the top surface of the nozzle plate, diameter of the discharge hole 2, and height H of the groove bank 4 from the bottom 3° of the circumferential groove 3 to the top surface 4' of the groove bank 4. each size of
and their respective relationship ratios. That is, the ratio A/D of the width A of the trench bank 4 to the hole diameter is preferably 0.5 to 5.
The value of ^/D is particularly preferably 0.8 to 3. If it is too large, the adhesion area of the ejected matter will become large and the spinnability will be reduced, and if it is too small, the creation process will be difficult. The ratio B/D of the width B of the circumferential groove 3 and the hole diameter is preferably 1 to
1O, and if 8/D is made large, temperature unevenness will occur when the inner surface of the circumferential groove 3 is affected by the cooling air, and if it is too small, machining will be difficult in this case as well. It is 5. The ratio H/C of the height H of the groove embankment 4 and the depth C of the circumferential groove 3 is preferably 0.02 to 1.5, and H/C
As the value increases from around 1.0, it is affected by the blowing wind, and the groove bank 4 plays the role of cooling fins, affecting the spinnability.If it becomes extremely small, it becomes difficult to work, so especially Preferably it is 0.2 to 0.95.

The fiber-forming substance is introduced into the introduction hole 5 of the nozzle plate having the above structure.
From there, it is guided to the discharge hole 2 via the connecting pipe 6.

Fibers are formed by extrusion.

(Example) The present invention will be described in more detail with reference to Examples below.

Example Stainless steel (S) with a diameter of 30 mm and a thickness of s
One discharge hole 2 having the structure shown in FIGS. 2 and 3 was bored in the center of the nozzle plate 1. The dimensions of the liquid hole 2 are as follows: Width A of the groove bank 4 = 0.3 arm, Width B of the circumferential groove 3 - 0.5 mm, Depth C of the circumferential groove 3 = 0.3 mm.

Pore diameter D = 0.31111. Diameter of introduction hole 5 E-3ms+
, Length F of introduction hole 5 = 4 mm, Length G of joint pipe 6 = 0
．． 0 mm.

Height of trench embankment 3 H = 0.27 mm, length of discharge hole 2 L = 0
．． At 97mm, A/D = 1.0.8/D-1,67
, 8/C=0.9. L/D is -3.23.

The spinnability test using the above-mentioned nozzle plate was conducted using a Koka type flow tester (this test machine can be considered as a constant pressure spinning machine) using pitch as the fiber forming material. The pitch used had a softening point of 165° C., a carbon content of 94%, and haloga due to 002 reflection was observed in the powder X-ray diffraction photograph. The average molecular weight estimated from gel permeation chromatography of the tetrahydrofuran soluble portion was about 400. The melt viscosity measured with a Koka type flow tester was 19.8 poise at 210°C, and the apparent activation energy obtained by changing the viscosity with temperature was 56.7 Kcal/mol.

The spinning test was conducted 10 times, each time changing the spinning temperature and/or pitch discharge speed. The pitch spun into the air from the discharge hole of the nozzle plate was formed into pitch fibers with an average diameter of 20 μm by controlling index thinning by air sucker.

The test results regarding spinnability are shown in Table 1.

In the table, Q is the discharge amount, and the take-up speed (■) is a value calculated from the pitch discharge speed obtained from experiments and the diameter of the obtained fiber.

The adhesion status of the pinch discharged from the discharge hole to the vicinity of the hole was evaluated visually using a 10x magnifying glass, and was evaluated in four stages: ◎ No adhesion, O slightly adhering, Δ equivalent adhesion, × Significant adhesion. . In addition, the evaluation of fineness unevenness of the obtained fibers was as follows:
Visual inspection was performed using a 100x optical microscope; 0: No spots, O: Some spots.

It was evaluated using a four-level evaluation system: Δ Considerably mottled, × Significantly mottled.

Further, the yield was expressed as the weight % of the obtained pitch fibers based on the charged pinch. In this case, it is unavoidable that the cylinder and part of the plunger of the Koka type flow tester will be pinched, so even if completely ideal spinning is performed, the yield will be 10%.
It is not possible to achieve 0%.

Table 1 Next, as a comparative example, diameter 30a++w, thickness 5IIl-
One 2° discharge hole of the conventional structure shown in FIG. 4 was bored in the center of a stainless steel (SUS316) type nozzle plate. The dimensions of each part of this discharge hole 2'' are the hole diameter D'-
0.3 mm, diameter of introduction hole 5゛ E' -3,01111,
Length of joint pipe 6° G'"0.0 +wa, 2" of discharge hole
L''/D''-3.33 at length L'-1.0 mm, spinnability test was carried out in the same manner as in Examples.

The results are shown in Table 2.

Table 2 Comparing and contrasting Tables 1 and 2, it is clear that the method of the present invention is superior to the conventional method.

(Effects of the Invention) Since the method of the present invention has the above-mentioned configuration, when spinning a low-molecular-weight polymer that has extremely poor spinnability as a fiber-forming substance, the method of the present invention can be applied to the circumferential groove of the nozzle plate and This had a mysterious effect, and we were able to obtain significantly improved spinnability compared to conventional products.

[Brief explanation of drawings]

FIG. 1 is a plan view of a spinning nozzle plate according to an embodiment used to carry out the method of the present invention, FIG. 2 is an enlarged plan view of one of the discharge holes of the plate and its surroundings, and FIG. FIG. 2 is an enlarged longitudinal cross-sectional view, and FIG. 4 is an enlarged longitudinal cross-sectional view of a discharge hole of a conventional spinning nozzle plate. 1--Nozzle plate, 2--Discharge hole, 3--Peripheral groove, 4--Full, 5--Introduction hole, 6-Joint pipe Patent applicant Unitika Co., Ltd. Ta30 NeφS

Claims (2)

[Claims] (1) A method for spinning a low molecular weight polymer, characterized in that a nozzle plate having a desired number of discharge holes in which circumferential grooves at predetermined intervals around the holes are cut for each hole is used during spinning. . (2) The spinning according to claim 1, wherein the ratio of the depth C of the circumferential groove to the height H of the circumferential bank cut between the discharge hole and the circumferential groove is 0.02 to 1.5. Method.