JPH0647314B2 - Method for manufacturing screen gauze - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a screen gauze made of polyester monofilament for printing. More specifically, the present invention relates to a method for removing defects caused by abrasion of a polymer that occurs when a screen gauze is manufactured.

[Prior Art] Polyester monofilament as a material constituting a screen mesh for printing has been highly used in recent years because of its high elasticity, durability and precise image printing. In particular, screen gauze used for printing electronic circuits uses polyester monofilaments having a denier of 20 denier or less, and even 12 denier or less to make a high-density woven fabric, but the reed width should be very narrow. The polyester surface is fibrillated due to repeated rubbing caused by beating, and fine fibril aggregates of various sizes are generated. Become an adhesive,
It is attached to or woven into monofilament fabric. This is called scum. When the scum is finished as a screen gauze, an inspection process is provided and this is manually removed, but when making a printing plate, for example, after covering the frame with a gauze, spraying with high pressure steam etc. taking it.

[Problems to be Solved by the Invention] In the prior art, the adhered scum is removed by washing or spraying with a high-pressure fluid, or part of it is removed by scouring which is a finishing step as a screen gauze. The scum woven into the screen gauze could not be removed. If such a defect is very large, it can be found by direct observation with the naked eye or a magnifying glass, so it is not necessary to use the defect part, but if the defect is too small to be seen by direct observation, use the printing plate. It is first discovered at the stage of making or finishing as a printed product, and it is extremely important to surely remove such minute defects, and a technology for improving the yield of such printed products is required. It was a coveted one.

[Means for Solving Problems] The object of the invention described above is to use a woven fabric made of polyester monofilament in which 80 mol% or more is an ethylene terephthalate unit in an amount of 5% by weight or more in a solvent that dissolves the polyester mainly containing caustic soda. This can be achieved by a method for producing a screen gauze, which comprises performing a weight reduction treatment and then washing with water.

Although the object of the present invention is to remove minute scum,
Since the specific surface area of scum is much larger than that of the polyester monofilament itself, even a slight weight reduction treatment is effective.

In the present invention, a solvent capable of dissolving the polyester mainly composed of caustic soda is caustic soda that accounts for more than half of the eluted components, and other caustic potash, other inorganic alkali compounds, organic alkali salts such as quaternary ammonium salts, etc. It may be contained, and those solutes are dissolved in water.

Further, the weight reduction treatment in the present invention may be any method as long as it is a method capable of removing scum, but it is preferable to heat a 2 to 10% caustic soda aqueous solution at 50 ° C. or higher. Do the weight loss treatment by dipping the woven screen gauze into the
It is also possible to apply a 20-30% high-concentration aqueous solution of caustic soda to a woven screen and leave it at room temperature for a long time, or after leaving it for a short time, spray steam. Immediately after the weight reduction treatment, it is important to wash with sufficient water or hot water to wash away the adhering alkali and scum. Then dry and heat set. The weight reduction rate at this time need not be specified as long as scum can be removed, but it is 5 to 20 for the following reason.
It is preferably in the weight%. That is, a very small weight loss rate is required for removing scum that can be found on the order of a microscope, and a high weight loss rate is preferable for removing large scum that can be visually recognized. When the weight reduction treatment of the present invention is carried out in an amount of more than 20% by weight, a considerably large scum is removed, which is preferable for the purpose of reliable scum removal. However, since the monofilament becomes thin, misalignment occurs at the intersection point of the history. It is not preferable because it becomes easy.

On the other hand, when the weight reduction rate is less than 5% by weight, the yield rate of the plate-made product may sometimes decrease.

As a technique similar to the present invention, there is Japanese Patent Publication No. 46-43134. The invention is mainly composed of sodium hydrate and other alkali compounds and alkali salts, and swells the surface of the polyester screen woven yarn with a liquid mixed with ethers and esters of polyhydric alcohols, and rubs it by physical treatment. It is a plate-making pretreatment method for facilitating sticking of a photosensitive emulsion or an exposed film film by forming a slightly rough surface. In the invention, the polyester is not dissolved in an alkaline solution but is allowed to swell. A dilute solution is applied at a low temperature (45 ° C.), and after holding for 5 to 7 minutes, a fine roughening treatment is performed. Even large scum cannot be removed by the treatment of the present invention, and after the swelling treatment, it is finely roughened by physical friction, so that fibrillation is promoted again here, and the object of the present invention is not achieved.

In the present invention, it is important to wash with water immediately after the weight reduction treatment. It is for the purpose of surely stopping the weight reduction process and not generating scum again by moving the screen mesh during the waiting time or the transfer time to the subsequent process.

Polyester in the present invention is composed mainly of a terephthalic acid unit and an ethylene glycol unit,
If the mol% or more is an ethylene terephthalate unit, a copolymerization component may be included if necessary.

A part of the unit of terephthalic acid is, for example, a monoalkali metal salt of 5-isophthalic acid, isophthalic acid, diphenoxydicarboxylic acid, 1,2-diphenoxyethane-p, p '.
-Replace with a dicarboxylic acid such as dicarboxylic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, dodecanedioic acid or an ester thereof, or an oxycarboxylic acid such as p-oxybenzoic acid, p-β-oxyethoxybenzoic acid or an ester thereof. A part of the ethylene glycol unit may be used, for example, alkylene glycol having 3 to 10 carbon atoms, 1,4-cyclohexanedimethanol, 1,4-bis (β-oxyethoxy) benzene, bisphenol A.
It may be replaced with a glycol such as bisglycol ether or polyalkylene glycol. Furthermore, it is also possible to use a small proportion of a chain branching agent such as pentaerythritol, trimethylolpropane, trimellitic acid and trimesic acid, and a polymerization terminator such as monohydric polyalkylene oxide and phenylacetic acid.

To produce polyester from such raw materials, for example,
Ethylene glycol ester of terephthalic acid and / or its low content can be obtained by transesterification of dimethyl terephthalate with ethylene glycol, direct esterification reaction of terephthalic acid with ethylene glycol, or addition reaction of terephthalic acid with ethylene oxide. The most widely adopted method is to synthesize a polymer and then subject the product to a polymerization reaction by a usual method. Further, in synthesizing the polyester for carrying out the present invention, a catalyst, an ultraviolet absorber, an anti-coloring agent, a matting agent, an ether bond by-product preventing agent, an antioxidant, a flame retardant and the like well known in the art may be appropriately used You can In the screen gauze made of polyester multifilament, scum is remarkably generated when a single yarn denier of 20 denier or less, especially 6 to 15 denier is used, but the treatment method of the present invention is effective in the range of denier. Act on.

[Examples] The present invention will be described in more detail with reference to Examples.

Example 1 and Comparative Example 1 A screen woven fabric was made using the polyester monofilament made of polyethylene terephthalate shown in Table 1.

This was divided into two, and one was immersed in a 5% caustic soda aqueous solution at 98 ° C for 50 minutes, washed with water, and finish-set to give a screen gauze having a history of 305 mesh (A). The weight loss rate of this screen gauze (A) was 8%. The other one is soda ash, Sandet G-29 1g / each
Was dissolved in water, scoured at 80 ° C. for 20 minutes, then finish-set and made into a screen gauze having a history of 305 mesh as in (A) (B). Table 2 shows the results of a defect investigation of these two types of screen gauze.

The screen gauze (A) subjected to the alkali weight reduction treatment had drastically reduced defects due to scum as compared with the screen gauze (B) which was not treated.

[Effects of the Invention] According to the production method of the present invention, (1) it is possible to significantly reduce the defects caused by the scum of the polyester screen gauze, and (2) it is discovered after the conventional printing plate making or after printing. It is possible to prevent such a drawback from occurring.

Claims (1)

[Claims] 1. A screen gauze characterized by subjecting a woven fabric comprising polyester monofilaments containing 80% by mole or more of ethylene terephthalate units to a weight reduction treatment of 5% by weight or more with a solvent composed mainly of caustic soda, and then washing with water. Production method.