JPH02127513A - Polyester monofilament for screen gauze - Google Patents

Abstract

PURPOSE:To obtain the title monofilament producing screen original sheets for higher IC substrate printing, forming a little scum of white powder in weav ing, having intrinsic viscosity, elongation at break, strength at break and tensile strength in elongation in specific ranges, respectively. CONSTITUTION:The aimed polyester monofilament having 0.7-1.0 intrinsic viscos ity, 35-50% elongation at break, >=5.0g/de strength at break and >=3.25g/de tensile strength at 10% elongation. The monofilament, for example, is obtained by extruding a polyester having 0.8-1.2 intrinsic viscosity at 295-300 deg.C in molten state while heating space right under a spinneret at 300 deg.C, successively taking-off the extruded yarn at 600-900m/minute while cooling and solidifying the extruded yarn, preheating the yarn at 95-115 deg.C high temperature and drawing while draw ing the prepared undrawn yarn at 3.4-4.5 times draw ratio, further heat-treating at 150-180 deg.C high temperature while drawing under tension and winding the drawn yarn at 600-800m/minute.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a polyester monofilament for screen gauze, and more specifically, to a polyester monofilament for use in screen gauze, and more specifically, to produce screen gauze with low white powder scum during weaving (and to efficiently produce screen gauze of excellent quality). This invention relates to a polyester monofilament that can be used as a polyester monofilament.

[Conventional technology]

Polyester monofilament, especially polyethylene terrestrial monofilament, has many excellent properties and has traditionally been used for screen gauze.In recent years, it has also entered the fields of electronics and high-end printing, and monofilament has become finer and more highly woven. There are increasing demands for stronger strength and durability.

However, when weaving screen gauze using this polyester monofilament, white powder scum is likely to occur and cause various problems.

Problems caused by the generation of white powder scum are particularly common when weaving high-density screen gauze of 260 or more meshes using polyester monofilaments with a fineness of 20 deniers or less as warp threads. This white powder scum is generated by repeated rubbing of the reed, and when using polyester monofilament with a fineness of more than 20 deniers, the reed width (the gap between the reed and the cross-sectional diameter of the filament)
Since the area is wide, the degree of abrasion is light (and its effect is small).Furthermore, since the fineness is large, there is little actual damage to the gray fabric from the white powder scum generated.

However, when polyester monofilament with a fineness of 20 deniers or less is used, the reed gap is usually smaller than the filament diameter, so the filament is repeatedly subjected to strong abrasion, resulting in significant surface damage and white powder scum.

Therefore, this white powder scum clogging causes warp thread breakage and warp streak spots on the gray fabric, resulting in a significant deterioration in both quality and production efficiency.

In order to solve this problem, the elongation at break is 30 to 60%.
It is known from JP-A-55-16948 that it is effective to use a polyester monofilament. However, although this polyester monofilament is effective in preventing the generation of white powder scum, since it uses a high elongation monofilament, the strength of the monofilament inevitably decreases, and it is elongated by rubbing under high tension during screen gauze weaving. There are problems in that the gauze tends to have warp streaks, its tensile strength is low, and its dimensional stability is reduced.

[Problem to be solved by the invention]

The present invention was developed against the background of the above-mentioned problems of the prior art, and therefore produces less white powder scum when weaving screen gauze, has high tensile strength, has excellent dimensional stability, reduces the occurrence of warp lines in gauze, and improves quality. An object of the present invention is to provide a polyester monofilament for high-grade screen gauze, which is suitable for producing high-density screen gauze.

[Means to solve the problem]

The present invention provides that a monofilament made of polyester is
This is a polyester monofilament for screen gauze characterized by simultaneously satisfying the following (a) to (d).

(B) 0.7≦Intrinsic viscosity≦1.0 (B) 35≦Elongation at break (%)≦50 (C) 5.0≦Strength at break (g/de) (D) 3.25≦10% elongation Tensile strength (g/de) The polyester monofilament of the present invention is mainly a monofilament made of polyethylene terephthalate. However, it may also be a polyester in which ethylene terephthalate is the main repeating unit and a small proportion (usually 20 mol % or less) of a third component other than terephthalic acid and ethylene glycol is copolymerized and/or mixed.

This monofilament may be melt-spun and drawn as a multifilament and then split, or it may be melt-spun and drawn as a monofilament from the beginning.

The polyester monofilament of the present invention has a fineness of 20
The effect is remarkable when targeting monofilaments of denier or less. Items with fineness greater than 20 denier,
Not only does it generate less white powder scum, but it is also used for relatively low mesh, and is often used in applications that do not require high precision printing, and does not require strict dimensional stability of the gauze.

However, although the present invention is particularly effective for monofilaments with a fineness of 20 deniers or less, it goes without saying that monofilaments with a fineness of more than 20 deniers may also have the physical properties defined in the present invention.

The monofilament of the present invention has an intrinsic viscosity of 0.7 to
It is necessary to be within the range of 1.0.

If the intrinsic viscosity is less than 0.7, it will be difficult to achieve the high strength and high elongation physical properties of the present invention, and it will also be difficult to reduce white powder scum during gauze weaving under high tension. On the other hand, if the intrinsic viscosity exceeds 1.0, the intrinsic viscosity of the polyester polymer used during melt spinning must normally exceed 1.2 (i.e., because the polymer decomposes due to heat and moisture during melting,
(The intrinsic viscosity of the polymer needs to be higher than that of the yarn), making melt spinning difficult.

Here, the value of the intrinsic viscosity was measured using a 10-chlorophenol solution at 25°C.

Furthermore, as shown in FIG. 1(A), the monofilament of the present invention is characterized by high strength, high elongation, and high tensile strength at 10% elongation.

Figure 1 shows the strength and elongation curves of polyester monofilaments, in which (A) is the polyester monofilament of the present invention, and (B) is the conventional polyester monofilament, which has good dimensional stability during gauze weaving. Polyester monofilament, which generates a lot of white powder scum when
(C) is a conventional polyester monofilament, which is effective against white powder scum, but has poor dimensional stability. In addition, in Figure 1,
Ej2 is the elongation at break, E i! ,+. is lO% elongation, st
is the tensile strength at break, SL. is the tensile strength at 10% elongation.

The elongation at break of the polyester monofilament of the present invention is
It is necessary that it is 35-50%, preferably 40-50%. Here, if the elongation at break is less than 35%, the scum reduction effect during weaving is insufficient, if it exceeds 35%, the white powder scum reduction effect increases, and in the range of 40 to 60%, the scum reduction effect is maximum. becomes. On the other hand, the elongation at break is 50
%, it is difficult to increase the tensile strength and the dimensional stability is poor.

Thus, the elongation at break of polyester monofilament that can achieve the object of the present invention is 35 to 50%.

Further, the polyester monofilament of the present invention needs to have a tensile strength of 5.0 g/de or more, and a tensile strength at 10% elongation of 3.25 g/de or more. Here, monofilaments with a breaking elongation of less than 5.0 g/de and a tensile strength at 10% elongation of less than 3.25 g/de have low tensile strength, so they cannot be used under high tension due to the reed during gauze weaving. As a result of abrasion, weak points in some areas undergo large elongation in other parts, causing warp spots and sagging of the gauze, resulting in a problem of deterioration of the quality of the gauze.

On the other hand, polyester monofilament, which has a breaking elongation of 5.0 g/de or more and a tensile strength at 10% elongation of 3.25 g/de or more, can effectively solve these problems and produce high-quality gauze. Obtainable.

The strength and elongation curve of the polyester monofilament of the present invention having such physical properties is shown in FIG. 1 as described above.

The method for producing the polyester monofilament of the present invention includes determining the intrinsic viscosity of the polyester to be subjected to melt spinning,
It can be obtained by appropriately adjusting melt spinning conditions and stretching heat treatment conditions. For example, while heating the area immediately below the spinneret to about 300°C, the intrinsic viscosity is 0.8 to 1. 2
of polyester is melted and discharged at a temperature of 295 to 300°C, and while the discharged yarn is subsequently cooled and solidified, a polyester of 600 to 90% is
00 m/min, and then the obtained unstretched system was subjected to 3.
When stretching at 4 to 4.5 times, the film is preheated at a high temperature of 95 to 115°C and further stretched to 150 to 180 degrees under stretching tension.
It is obtained by subjecting it to high-temperature heat treatment at C and winding it up at a stretching speed of 600 to 800 m/min.

Here, in order to obtain a polyester monofilament having the physical properties of the present invention, it is important to use a polyester whose intrinsic viscosity is larger than the usual 0.65, preferably 0.75 or more, and to Intrinsic viscosity 0.7~
1.0, and after spinning at low speed, high-magnification, high-temperature stretching, and high-temperature heat treatment, it is possible to simultaneously achieve high breaking strength, strength at 10% elongation, and high breaking strength. That is, in order to improve the strength properties, it is common to stretch at a high magnification, but it is difficult to simultaneously improve the elongation properties. Therefore, in this polyester monofilament manufacturing method, the normal stretching temperature is 85 to 95.
By setting the temperature higher than that of °C, stretching is performed while relaxing the local strain of the internal structure due to stretching. Thereby, stress concentration during local elongation can be suppressed, and elongation characteristics can be improved. Furthermore, since high-magnification stretching is also possible at the same time, it is possible to improve the breaking strength and the strength characteristics at 10% elongation. Furthermore, the normal heat treatment temperature is 145
By performing high-temperature heat treatment at 150 to 180°C compared to 150°C, the strength properties can be improved by developing the crystal structure.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, the strength and elongation in the examples are those of Instron TM-M type (
This is the strength elongation on the stress-strain curve measured with a filament length of 20cm (manufactured by Instron, USA).
m, stretching speed 100%/min, temperature and humidity 20°C x 6
This is the average value of strength and elongation obtained by repeatedly measuring each burn 5 times for arbitrary 10 burns under the condition of 5% R1.

Example 1 Polyethylene terephthalate polymers with various intrinsic viscosities are used, melted so that the polymer temperature at the time of discharge is 295°C, and the fineness after stretching from a nozzle with a pore diameter of 0.65 becomes a predetermined fineness. The material was discharged as shown in FIG. Next, it was stretched at various magnifications, and as shown in Table 1, it had a denier of 9 to 22, an elongation at break of 30 to 53%, a strength at break of 4.8 to 5.8 g/de, 1
Various polyester monofilaments having a tensile strength at 0% elongation of 2.8 to 4.2 g/de were obtained.

These monofilaments were rubbed under the following conditions and the amount of white powder scum generated was compared, and the results are shown in Table 1.

In the abrasion test, a monofilament with a thread length of 20 m was
The monofilament was hooked 30 times in parallel at a pitch of 0.3 mm to two gripping rods facing each other at an interval of , and fixed under a tension of 3 g. ) and rubbed at a speed of 400 times/min for 120 minutes, the amount of scum attached to the monofilament was observed and graded into the following three grades.

◎; Almost no white powder scum is generated.

○: There is little white powder scum.

×; There is a lot of white powder scum.

Further, the obtained monofilament was partially warped to have a warp count of 10,177, and the same monofilament as the warp was used as the weft to weave 300 meshes of screen gauze at a speed of 180 times/min using an ordinary textile machine. . The weaving results are also shown in Table 1.

Here, the gauze quality A reversal rate is determined by scores such as warp breakage due to white powder scum clogging, warp streak spots on the gray fabric, warp streaks due to reed scratches during weaving, and looseness. It is called the A-rejection rate and indicates the passing rate.

Note that the A reversal rate is set at 92% or more as an acceptable line.

In addition, in Table 1, in Experiment Nos. 1 to 17, high-temperature heat treatment was performed at a preheating temperature of 105' C1 heat treatment temperature of 170° C. during stretching, and monofilaments with predetermined physical properties were obtained. Furthermore, in Experiment Nos. 18 to 21, stretching was carried out at a preheating temperature of 90°C and a heat treatment temperature of 145°C.
A monofilament having the physical properties shown in the table was obtained.

As shown in Table 1, monofilaments with physical properties satisfying the present invention (Experiment No. 4-12, 16-1 in Table 1)
In sample 7), the white powder scum was good and the quality of the gauze was also good, indicating that the monofilament of the present invention is excellent.

〔Effect of the invention〕

The gauze made of polyester monofilament for screen gauze of the present invention produces less white powder scum during weaving, has excellent gauze quality, and is suitable for use in high-grade IC fabrics made of high-density screen gauze.
It can be used as a screen original plate for substrate printing.

[Brief explanation of the drawing]

FIG. 1 shows the strength and elongation curves of polyester monofilaments, in which (A) is an example of the polyester monofilament of the present invention, and (B) and (C) are examples of conventional polyester monofilaments. In FIG. 1, El is the elongation at break, Effi. is 10
% elongation, st is breaking strength, St+. indicates the tensile strength at 10% elongation.

Claims (1)

[Claims] (1) A polyester monofilament for screen gauze, characterized in that the monofilament made of polyester simultaneously satisfies the following (a) to (d). (B) 0.7≦Intrinsic viscosity≦1.0 (B) 35≦Elongation at break (%)≦50 (C) 5.0≦Strength at break (g/de) (D) 3.25≦10% elongation tensile strength (g/de)