JPS59207289A - Polyester monofilament compound yarn for screen gauze - Google Patents

Abstract

PURPOSE:To obtain polyester monofilament compound yarn of which screen gauze free from white powder falling-off and halation is composed by a method wherein the compound yarn has a concentric composition of a core and a sheath and the cross sectional area and the thickness of the sheath are specified and the content of titanium oxide of the sheath is suppressed to lower than that of the core. CONSTITUTION:Polyester monofilament compound yarn has a concentric composition of a core and a sheath. The thickness of the sheath is not less than 2mum and the corss sectional area of the sheath is not more than 60% of the cross sectional area of the said compound yarn. The content of titanium oxide of the core is not less than 0.3wt% and the content of titanium oxide of the sheath is a half of that of the core or the sheath is made of polyester which does not contain titanium oxide at all. With this constitution, the required compound yarn is obtained. These yarns are spinned by a known spinner. EFFECT:Stable screen gauze products can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyester monofilament composite yarn for screen gauze.

Conventional polyester monofilaments for screen gauze are produced by melt-spinning and drawing a single polymer using a conventional method to obtain a multifilament, dividing the obtained multifilament into monofilaments, and by melt-spinning and drawing a monofilament by a conventional method. The method of obtaining this information is adopted. A method for manufacturing monofilaments by splitting multifilaments is disclosed, for example, in Japanese Patent Application Laid-Open No. 56-37962.

The outline of the manufacturing process for screen gauze base fabric and printed circuit boards is as follows: monofilament atoms → warping → weaving → screen gauze base fabric → heat setting → frame stretching → photosensitive emulsion coating → master plate baking →
It goes through a variety of manufacturing processes: washing with water → screen gauze original board → board printing → etching → printed circuit board. The density of the screen gauze is generally in the range of 100 meshes to 500 meshes when polyester monofilament yarn is used.

With conventional polyester monofilaments for screen gauze, during the manufacture of the screen gauze described above, white powder falls off due to repeated strong abrasions during weaving, and so-called halation occurs where parts other than the predetermined light projecting areas are exposed to light reflected during printing of the original sheet. This was a major drawback and an issue to be considered. If there is a lot of white powder falling off, the white powder will stain and clog the reed during weaving, causing troubles such as thread breakage and staining of the gray machine, making it impossible to maintain the weaving length and significantly reducing work efficiency.

Furthermore, if halation occurs, it not only seriously deteriorates the quality of the substrate, but also makes it difficult to print the substrate with greater precision.

To address the above-mentioned drawbacks, conventional weaving methods have been to reduce the weaving length to prevent white powder from falling off during weaving, and to dye the base fabric, for example, in a yellowish color, to prevent halation from occurring during printing. The reality is that we are dealing with formulations that are inefficient in production, such as dyeing them in colors that absorb ultraviolet rays. In addition, since the raw thread of polyester monofilament for screen gauze has conventionally been composed of a single polymer, these drawbacks can be solved by (1) suppressing thread friction during weaving;

(2) Take measures to prevent halation when printing the original plate.

In the case of (1), it is affected by, for example, the type and content of titanium oxide and other matting agents contained in the polyester monofilament, the type and amount of adhering oil, etc. However, the smaller the content or adhesion, the better. In the case of (2),
For example, it is influenced by the content of titanium oxide and other matting agents contained in the polyester monofilament, and the higher the content, the better.

Therefore, contradictory measures are required to address the above-mentioned drawbacks.

In addition, as a solution to the drawback, a method of adding an antihalation agent to the polymer by suppressing the addition of titanium oxide or other matting agents contained in the polymer with a single polymer composition has been attempted, but many This method involves problems and requires a large amount of investment, so it is not necessarily a good idea from an industrial perspective.

The inventors of the present invention have conducted various studies to solve the above-mentioned drawbacks, and as a result, the present inventors have taken measures to prevent white powder from falling off during weaving on the surface of the polyester monofilament raw yarn for screen gauze (sheath portion as referred to in the present invention). In order to prevent halation inside the yarn (the core in the present invention), we mainly use a core-sheath type polyester monofilament composite yarn that has a difference in titanium oxide content between the sheath and the core. The present invention was achieved by finding a way to solve these drawbacks.

That is, the present invention provides a composite yarn having a concentric core-sheath structure, a thickness of the sheath portion being 2μ or more, and a cross-sectional area of the sheath portion being 60% or less of the cross-sectional area, A polyester monoester for screen gauze made of polyester with a titanium oxide content of 0.3% by weight or more and a titanium oxide content in the sheath of 1/2 or less of the titanium oxide content in the core, or a sheath containing no titanium oxide. It is a filament composite yarn.

The polyester monofilament referred to in the present invention is primarily a monofilament made of polyethylene terephthalate, but it is a copolymerized polyester containing 95 mol% or more of polyethylene terephthalate units or a base material of polyethylene terephthalate that is 2 weight % or less of other polymers may be mixed. Furthermore, the polymers in the sheath and core portions that make up the monofilament composite yarn are mainly targeted at the difference in content of titanium oxide, but matting agents such as pigments and dyes in place of titanium oxide are also included.

The polyester monofilament composite yarn of the present invention must have a concentric core-sheath structure, and the thickness of the sheath portion must be 2μ or more. If the sheath thickness is less than 2 μm, stable concentric core-sheath type composite melt spinning will be difficult, and the yarn will be rubbed during the screen gauze manufacturing process and the core polymer will be exposed on the yarn surface, resulting in white powder falling off, yarn breakage, etc. There are problems that cause process troubles.

The content of titanium oxide in the core is less than 0.3% by weight, and if the area of the sheath exceeds 60% of the cross-sectional area of the thread, it is difficult to suppress halation that occurs during printing of the original plate in the screen gauze manufacturing process. It is. Furthermore, if the titanium oxide content in the sheath exceeds 1/2 of the oxidation techno content in the core, the function of the polyester monofilament composite yarn of the present invention will be lost, and white powder will be prevented from falling off during weaving in the screen gauze manufacturing process. The effects of this are not fully recognized. It is desirable that the content of titanium oxide in the sheath portion be suppressed to no content or to 0.3% by weight or less, preferably 0.1% by weight or less.

Further, the fineness of the polyester monofilament composite yarn after drawing is preferably about 5 to 40 de.

A preferred embodiment of the method for manufacturing the novel polyester monofilament composite yarn for screen gauze described above will be described. A conventionally known device can be used for the composite spinning method. FIG. 1 is a schematic diagram showing a preferred example of a composite spinning apparatus used in the present invention. In Figure 1, the hopper 1x has a core polymer X and the hopper 1y has a sheath polymer Y.
are charged, each is melted using extruders 2x and 2y, and measured using gear pumps 3x and 3y, extruded from a spinneret 4 to form thread 5, and wound up using a winder (not shown) to obtain an undrawn thread.

FIG. 2 is a cross-sectional view showing the main part of the spinneret, and FIG. 3 is a cross-sectional view of an undrawn yarn obtained by composite spinning.

The core polymer X is composited so as to be surrounded by the sheath polymer Y at the meeting point P of the mouthpiece 4, and is discharged to form a composite yarn. The cross-sectional shape of the undrawn yarn is concentric circles as shown in FIG. The undrawn yarn obtained by composite spinning is drawn as a monofilament or multifilament using a drawing method.

In the case of multifilament, it is drawn and divided into monofilament composite yarns. In the case of a multifilament, it may be split at the time of spinning and winding, wound up as a monofilament, and then stretched, or alternatively, the effect of the present invention will not essentially change even if the monofilament is split after stretching.

Therefore, the polyester monofilament composite yarn for screen gauze of the present invention is a core-sheath type composite yarn, has a concentric core-sheath structure, has a thickness of the sheath portion of 2μ or more, and has a cross-sectional area of the sheath portion. is 60% or less of the cross-sectional area, the titanium oxide content in the core is 0.3% by weight or more, and the titanium oxide content in the sheath is 1/2 of the titanium oxide content in the core.
It is constructed of polyester that does not contain titanium oxide in the lower part or the sheath part. The above-mentioned drawbacks can only be solved to the extent that these requirements are satisfied, and the yarn is much superior to polyester monofilament yarns for screen gauze obtained by any of the conventionally known methods. Furthermore, by using the polyester monofilament composite yarn for screen gauze of the present invention, it is possible to produce screen gauze products stably, which makes it even more useful for use in a variety of fields, and has extremely great industrial significance.

Examples of the present invention will be described in detail below.

Examples As core and sheath polymers, polyethylene terephthalate containing titanium oxide with various intrinsic viscosities [η] of 0.65 measured at 25° C. in ornochlorophenol solution,
The ratio of the core polymer to the sheath polymer was varied and the spinning temperature was 290.
Melt-spun using a composite thread-proof cap with 2 holes at 10°C.
The fibers were separated and wound at a speed of 00 m/min. The obtained undrawn yarn monofilament composite yarn was drawn by a conventional method to obtain 11 de-1 fil.
A drawn monofilament composite yarn having a breaking strength of 5.2 g/de and a breaking elongation of 38% was obtained. Table 1 shows the quality of the obtained yarn including the screen gauze processing results.

No. Examples 5 to 8 are comparative examples for clarifying the effects of the present invention.

As is clear from Table 1, No. No. 5 has a thick sheath which does not contain titanium oxide, and therefore has the disadvantage that during the manufacture of screen gauze, so-called halation occurs in which areas other than the predetermined light projecting area are exposed to light due to reflected light during printing of the original plate at the sheath. Also No. 6 has a thin sheath, which makes it difficult to perform stable concentric core-sheath type composite melt spinning, and when the thread is rubbed during the screen gauze manufacturing process, the polymer in the core is exposed on the thread surface and white powder falls off. , there are drawbacks that cause process troubles such as thread breakage.

No. No. 7 uses a polymer with a low content of titanium oxide in the core, so even if other requirements meet the provisions of the present invention, it is No. 7 in the production of screen gauze. It has the disadvantage of causing halation similar to No. 5. And No. 8
Since the sheath polymer contains more than a certain amount of titanium oxide, it has the disadvantage that it cannot sufficiently prevent white powder from falling off, which is a problem during weaving in the screen gauze manufacturing process.

On the other hand, monofilament composite yarns that satisfy the provisions of the present invention achieve the desired purpose.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a preferred example of a composite spinning apparatus used in the present invention. FIG. 2 is a cross-sectional view showing the main parts of the base portion in FIG. 1. FIG. 3 is a sectional view showing an example of undrawn yarn obtained by composite spinning. 1x, 1y: Popper 2x, 2y: Extruder 3x, 3y: Gear pump 4: Base 5: Yarn X: Core polymer Y: Sheath polymer

Claims (1)

[Claims] It has a concentric core-sheath structure, and the thickness of the sheath part is 2μ or more,
and a composite yarn in which the sheath area of the cross-sectional area is 60% or less of the cross-sectional area, the titanium oxide content of the core is 0.3% by weight or more, and the titanium oxide content of the sheath is 60% or less of the cross-sectional area; A polyester monofilament composite yarn for screen gauze characterized by having a titanium content of 1/2 or less or not containing titanium oxide in the sheath part.