JPS62215013A - Polyester monofilament for screen gauze - Google Patents

Abstract

PURPOSE:To provide the titled monofilament having breakage strength, breakage elongation, etc., satisfying specific conditions, stretchable over a frame under high tension, giving a gauze resistant to tearing and suitable for printing of IC substrate. CONSTITUTION:The objective monofilament is composed of a polyester (preferably polyethylene terephthalate) having a fineness of <=20 denier, preferably 9-17 denier and satisfying the following conditions at the same time. The elongation at break is 50-35%, the breakage strength St is >=5g/de and the ratio of St to St75 (St/St75) is >=1.10 (St75 is stress at an elongation corresponding to 75% of the elongation at break).

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a polyester monofilament for screen gauze suitable for gauze fabric for screen printing, and more specifically, it relates to a polyester monofilament for screen gauze that is suitable for gauze fabric for screen printing. This invention relates to a polyester monofilament for screen gauze that does not easily cause fraying.

(Prior art and its problems) Traditionally polyester monofilament.

In particular, polyethylene terephthalate monofilament
It is used in gauze fabrics for screen printing because it has many excellent properties.

In order to reduce the generation of white powder scum that becomes an obstacle when weaving high-density screen gauze with a mesh size of 260 or more using polyester filaments with a fineness of 20 deniers or less, the polyester monofilament used for weaving must have a breaking elongation. It is known from JP-A-55-16948 that it is effective to use a proportion of 35 to 60%.

However, even screen gauze using such polyester monofilament has a problem in that the gauze tends to tear during the frame stretching process during the production of a screen printing original plate. In particular, since high-precision printing is required for screen original plates for printing IC boards, the frame is stretched with relatively high tension in order to improve dimensional stability during printing, which can easily cause the gauze to tear. There is.

[Purpose of the invention]

Polyester 7 for screen gauze, which is less likely to cause stiffness when producing a screen printing original plate using density screen gauze, is less prone to tearing of the gauze during the framing process, and provides a gauze fabric with excellent dimensional stability after framing. The aim is to provide nofilament.

[Structure of the invention]

In order to achieve the above object, the present inventors first studied the physical properties of polyester monofilament that can prevent the gauze from tearing during framing, and found that the breaking strength was 5.5. ON/de
Based on the above, it has been found that in gauze using monofilament whose strength uniformly increases with elongation until breakage in the strength/elongation curve, the occurrence rate of gauze tearing during frame stretching does not decrease, and the present invention has been made. Reached.

That is, the present invention is a polyester hexafilament for screen gauze, characterized in that the monofilament made of polyester and having a fineness of 20 deniers or less simultaneously satisfies the following formulas 0 to 0.

■ 50≧Elongation at break ≧35 [chi] ■ St≧s, Q (!j/ds) ■ Upper≧1.10 St7゜ (St is the breaking strength * S t75 is the elongation at break 7
(strength at 5% elongation) The polyester monofilament of the present invention has a strength of 20
The effect is remarkable when targeting monofilaments with denier or less, especially monofilaments with a fineness of 9 to 17 deniers. Those with a fineness of more than 20 denier not only generate less scum, but also have a relatively low mesh and are often used for screen gauze for applications that do not require particularly high precision printing, and are used to create screen printing original plates. Since there is no need to increase the dimensional stability during printing by sometimes stretching the fabric under high tension, the gauze is less likely to tear when stretching the fabric.

The monofilament of the present invention is a polyester monofilament with a fineness of 20 de or less, has relatively high elongation and high strength, and has a strength and elongation curve as shown in Figure 1 (4).
), the strength increases uniformly as the elongation increases. Figure 1 shows the strength and elongation curves of polyester monofilament, where A is the polyester monofilament of the present invention and B is the strength of the gauze when stretched. Conventional polyester monofilaments that are prone to tearing are shown.

In the figure, El is elongation at break, EJ? , is El
75% elongation, St is breaking strength, St.

Is it E7? , respectively.

El of the polyester monofilament of the present invention is 35
It is important that the thickness is between 50 and 50 inches, preferably between 40 and 50 inches.

Here, when El is less than 35 inches, the scum reduction effect during weaving is not sufficient, when Ez is 35- or more, the white powder scum reduction effect increases, and when El is in the range of 40 inches to 60 To, the scum reduction effect is insufficient. is the maximum. On the other hand, monofilaments with an El of more than 50% tend to have poor dimensional stability, so the upper limit of El of a polyester monofilament that can easily achieve the object of the present invention is 50 inches.

Furthermore, the monofilament of the present invention has an St of 5-
0&/de or more preferably 5.0-6.01/d
It is important that e and S t / S tts be 1.10 or more, preferably 1.10 to 1.20.

The strength and elongation curve of such a polyester monofilament is shown in FIG.

Here, St is 5.0. ! ? In the case of conventional monofilament shown in FIG. 1 (BIK) where /de ungrooved monofilament or St/Sta is 1.10 unfi, the gauze tends to tear when stretched.

In this way, in the monofilament shown in Figure 1 (Bl),
The reason why the threads tend to tear when the frame is stretched is presumed to be as follows.

That is, since it is extremely difficult to completely eliminate tension unevenness in the gauze when it is stretched, high stress acts locally on the monofilaments that make up the gauze.

Even if such stress is less than the breaking strength (St) of the monofilament, for example, a stress of StS is applied, the conventional monofilament shown in FIG.
) Compared to the monofilament of the present invention shown in ℃, the difference in breaking strength (St) is small, so when a slight external force is applied, the total stress easily reaches St and breaks. .

In addition, in the present invention, the strength and elongation of monofilaments with a fineness of 20 deniers or less are specified, but
It goes without saying that even monofilaments (more than denier) may have a strength and elongation that simultaneously satisfies the 0 to 0 formula defined in the present invention.

The method for producing the monofilament of the present invention involves determining the intrinsic viscosity (■) of the polyester to be subjected to melt spinning;
It can be obtained by adjusting the melt spinning conditions and the stretching heat treatment conditions, and examples thereof will be shown below.

That is, the area directly below the spinneret surface is heated to approximately 300°C.
IV O, 65-1, 1, preferably 0.9-1
．． The polyester of No. 1 is melted and discharged at a temperature of 290 to 295°C, and then the discharged yarn is cooled and solidified.
The undrawn yarn was drawn at a rate of 900 g/min.
After stretching 4 to 4.5 times at a temperature of 0 to 95 °C, heat treatment at 145 to 150 °C under tension, and then stretching to 600 to 800 °C.
It can be obtained by killing 4 K/min.

At this time, it may be treated as a multifilament yarn between melt spinning and drawing heat treatment, and may be split into monofilaments after the drawing heat treatment, or may be processed as monofilament from the time of melt spinning.

In addition, the polyester as used in the present invention mainly refers to a polyester having terephthalic acid as the main acid component and ethylene glycol as the main glycol component.

In the present invention, the polyester may be a polyester in which a part of the terephthalic acid component is replaced with another functional carboxylic acid component, or a polyester in which a part of the ethylene glycol component is replaced with another diol component. . Examples of difunctional carboxylic acid components other than the terephthalic acid component used here include inphthalic acid, naphthalene dicarboxylic acid, diphenylcarboxylic acid, diphenoxyethane dicarboxylic acid, β-hydroxyethoxybenzoic acid + p-oxybenzoic acid! , 5-sodium sulfoisophthalic acid, 7
Aromatics such as divic acid, heptabasic acid, and 1,4-cyclohexane dicarbonate.

Examples include aliphatic and alicyclic difunctional carboxylic acid components. In addition, other diol components other than ethylene glycol include, for example, cyclohexane-1,4-dimetatool, neopentyl glycol, bisphenol A,
Examples include aliphatic, alicyclic, and aromatic diol components such as bisphenol S, and polyoxyalkylene glycol components.

Such polyesters may be synthesized by any method. For example, for polyethylene terephthalate (K), 1. Usually, terephthalic acid and ethylene glycol are directly esterified, or a lower alkyl ester of terephthalic acid such as dimethyl terephthalate is transesterified with ethylene glycol, or terephthalic acid is The first stage reaction is to react with ethylene oxide to produce glycol ester of terephthalic acid and/or its low polymer, and the reaction product of the first stage is heated under reduced pressure to reach the desired degree of polymerization. It is produced by a second step of polycondensation reaction. Moreover, arbitrary additives may be mixed into the polyester as required.

[Effect]

Generally, when stretching a frame, it is impossible to eliminate tension unevenness on the gauze, so high stress acts locally on the monofilament (K) that makes up the gauze.

In this point 1, the polyester monofilament of the present invention has
Compared to the conventional monofilament shown in Figure 1 (BIK), the difference between St and St is large, so even if the stress of S t, acts as a tension spot, there is sufficient margin up to St. Therefore, even if a slight external force is applied, the total stress does not reach St and the monofilament is difficult to break, so it is possible to prevent the gauze from tearing during framing.

Furthermore, the monofilament of the present invention has good weaving properties because the generation of white powder scum that impairs weaving properties can be extremely reduced during weaving.

〔Effect of the invention〕

The screen gauze made of polyester heptofilaments of the present invention can be used as a screen original plate for printing IC boards, which is stretched under high tension.

〔Example〕

Next, the present invention will be described in detail with reference to Examples.

In addition, the strong elongation in the examples is the strong elongation at the stress strain curve measured with an Ins + = N TM-M type (manufactured by Ins, Inc., USA), and the measured filament length is 20 elN.
+Stretching speed 100%, temperature and humidity 0℃ x 65cm
This is the average value of strength and elongation obtained through repeated measurements.

Example I A polyethylene terephthalate polymer with an IV of 0.95 was melted so that the temperature of the polymer at the time of discharge was 292°C, and the fineness after stretching from a nozzle with a pore diameter of o-'lsm was set to a predetermined fineness. The material was discharged into a single roll and wound up at a take-up speed of 1 minute.

Next, it was stretched at different magnifications in the range of 4.0 to 3.2, and as shown in Table 1, the fineness was 5 to 25 deniers and the elongation at break was 3.
A 0-53% polyester monofilament was obtained. These monofilaments were rubbed under the following conditions and the amount of white powder scum generated was compared, and the results are also shown in Table 1.

In the abrasion test, a monofilament with a thread length of 20 m was tested with 30 cn.
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 1 mm, and fixed under a tension of 3 Ii. Stainless steel) K through, 1 at a speed of 400 times/min.
After rubbing for 20 minutes, the amount of scum adhering to the monofilament was observed and graded into the following four levels.

◎ means almost no white powder scum occurs O means there is little white powder scum Δ means there is a lot of white powder scum 3 using the same monofilament and using a normal loom at a speed of 180 times/min.
00 mesh screen gauze was woven. The weaving results are also listed in Table 1.

The screen gauze was heat-set to obtain predetermined physical properties of the fabric, then stretched over a frame, and the results of determining the frequency of tearing are also listed in Table 1.

Comparative Example I I V A polyethylene terephthalate polymer with a strength of 0.65 was used, melted so that the temperature of the polymer at the time of discharge was 292°C, and the fineness after stretching from a nozzle with a pore diameter of 0.451ffl11 to a predetermined fineness. Discharge until 1400
One roll winding at a take-up speed of +a/min, then 3.6 to 3
．． The polyester monofilament was stretched at different magnifications in the range of 0 to 1, to obtain polyester monofilaments having a fineness of 17 to 20 deniers and a breaking elongation of 35 to 50 inches, as shown in Table 2. These monofilaments were subjected to a scratch test in the same manner as in Example 1, and the results are also shown in Table 2. Furthermore, the weaving results of the screen gauze obtained in the same manner as in Example 1 and the frequency of occurrence of tearing during framing are also listed in Table 2.

Example 2 A polyethylene terephthalate polymer with an IV of 0.65 was used and melt-spun in the same manner as in Example 1, resulting in an IV of 4.7~
The polyester heptanofilaments having a fineness of 17 to 20 deniers were obtained as shown in Table 3 by stretching at different magnifications within the range of 4.5.

Table 3 also shows the weaving results of the screen gauze obtained in the same manner as in Example 1 and the frequency of occurrence of tearing during framing.

[Brief explanation of drawings]

FIG. 1 shows the strength and elongation curves of polyester heptad filaments, one showing the polyester seven/filament of the present invention, and B showing the conventional polyester seven filament, which tends to tear the gauze during stretching. In the figure, El is the elongation at break tEJ? s is El's 75
% elongation, St represents the breaking strength, and St represents the strength corresponding to Els, respectively.

Claims (3)

[Claims] (1) A polyester monofilament for screen gauze, characterized in that the monofilament made of polyester and having a fineness of 20 denier or less simultaneously satisfies the following formulas [1] to [3]. [1] 50≧Breaking strength≧35 [%] [2] St≧5.0 [g/de] [3] St/St_7_5≧1.10 (St is the elongation at break and St_7_5 is the elongation at break 7
This is the strength at 5% elongation. ) (2) Fineness of polyester monofilament is 9 to 17
The polyester monofilament for screen gauze according to claim (1), which is a denier. (3) The polyester monofilament for screen gauze according to claim (1), wherein the polyester is polyethylene terephthalate.