JP4924504B2 - Polyester monofilament for screens - Google Patents

Description

  The present invention relates to a polyester monofilament for screen wrinkles that has high printing accuracy and dimensional stability, and has excellent weaving properties that do not cause scraping or scum during weaving.

  Currently, a screen fabric for printing uses a mesh fabric made of polyester or nylon in view of strength, dimensional stability, and cost. In particular, polyester mesh fabrics are widely used because they have excellent dimensional stability and are suitable for printing printed circuit boards that require high precision. However, when printing on electronic information materials in recent years, a higher level of printing accuracy is required. To meet this demand, it is necessary to make screens with higher strength and higher elasticity. In order to increase the strength and elasticity of polyester monofilaments, a method of drawing a high-viscosity polymer at a high magnification has long been used in the raw yarn manufacturing process. Therefore, the higher the orientation of the yarn oriented at a higher magnification, the easier it is to scrape the fiber surface into a knot-like shape. If it remains woven, there is a problem that directly leads to a defect. Further, since the loom is contaminated by the scraped scum, it is necessary to clean the loom regularly, and the more scum is generated, the lower the productivity.

As means for solving such drawbacks, many means have been proposed for prescribing the strength and elongation of the raw yarn and avoiding scraping and scum (Patent Document 1, etc.). However, in any case, it is premised on lowering the modulus of the raw yarn, and it is difficult to obtain the required high strength and high elasticity screen wrinkles. On the other hand, paying attention to titanium oxide in polyester, specific strength and dry heat shrinkage ratio using polyester containing 0.4 to 0.6% by weight of titanium oxide with an average particle size of 0.25 to 0.55 μm The monofilament which has is proposed (patent document 2). Certainly, by defining the average particle size, a certain effect can be seen in the generation of scum during weaving, but the particle size distribution of titanium oxide as well as the average particle size can be reduced in terms of scraping and scum generation during weaving. In particular, the existence ratio of the specific particle size range and the existence ratio of coarse particles above a certain value have a great influence, and even when the titanium oxide of the present invention has particularly high strength and high elastic modulus, it causes cutting and scum generation. There are cases where it cannot be avoided.
JP-A-55-16948 (Claim 1) JP-A-2-277818 (Claim 1)

  The present invention provides a monofilament that improves the drawbacks of the prior art and has less printing and scum during monofilament weaving and has high printing accuracy and dimensional stability.

  The object of the present invention can be achieved by the following. That is, titanium oxide having a particle size distribution in which 60% or more of the total number of particles has a primary particle size of 0.1 to 0.6 μm and particles having a primary particle size of 1.0 μm or more is 10% or less of the total number of particles. A monofilament for a screen wrinkle comprising polyethylene terephthalate containing 0.3 to 0.8% by weight, having a strength of 5.6 to 6.2 cN / dtex and an elongation of 25 to 35%.

  By using the polyester monofilament of the present invention, it is possible to obtain a monofilament for screen wrinkles that has high printing accuracy and generates less scraping and scum during weaving.

  The monofilament for a screen cage of the present invention needs to be made of polyethylene terephthalate from the viewpoint of weather resistance, dimensional stability, and mechanical properties. A small amount of a copolymer component may be contained as long as the purpose is not impaired. In addition, the intrinsic viscosity of the monofilament of the present invention is preferably 0.68 to 0.77 in view of the strength of the obtained monofilament and the stability of yarn production.

  In addition, as a result of intensive studies on scraping and scum generation during weaving of monofilaments, the present inventors have not only improved the weaving property of monofilaments, but also titanium oxide content in polyethylene terephthalate constituting monofilaments. It was found that the distribution state of the primary particle size greatly affects. That is, the monofilament for a screen wrinkle of the present invention needs to contain 0.3 to 0.8% by weight of titanium oxide, and 60% or more of the total number of particles has a primary particle size of 0.1 to 0.1%. It is necessary that particles having a particle diameter of 0.6 μm and a primary particle diameter of 1.0 μm or more have a particle size distribution that is 10% or less of the total number of particles.

  By making the content of titanium oxide 0.3% by weight or more, it becomes possible to sufficiently reduce the friction between the running yarn and the metal, and by making it 0.8% by weight or less, the desired raw yarn strength In addition, it is possible to suppress rubbing between the metal and the raw yarn that are in contact with each other during weaving. Preferably it is 0.4 to 0.6% by weight.

  Furthermore, 60% or more of the total number of titanium oxide particles has a primary particle size of 0.1 to 0.6 μm, and particles having a primary particle size of 1.0 μm or more are 10% or less of the total number of particles. is necessary. More preferably, 30% or more of the total number of titanium oxide particles is 0.2 to 0.4 μm, and 1.0 μm or more is 8% or less of the total number of titanium oxide particles. According to the study by the present inventors, scraping and scum at the time of weaving occurs starting from coarse particle portions present in the fiber surface, and even if the average primary particle size is defined within a specific range, the particle size distribution is When it is broad or coarse particles of 1.0 μm or more are mixed at a certain rate, it is impossible to avoid the occurrence of abrasion. In this way, by controlling the distribution of the primary particle diameter of titanium oxide contained in the monofilament to a specific range, it is possible to reduce the rubbing with the warp wrinkles as much as possible during weaving. In addition, when a large number of titanium oxide primary particle diameters smaller than 0.1 μm are present, when the monofilament is used, the friction on the fiber surface is increased, and the fiber itself is more likely to be scraped and becomes powdery. There is a problem that scum generation increases.

The method for controlling the particle size distribution of titanium oxide within the range of the present invention is not particularly limited. First, the titanium oxide to be added has 30 coarse particles of 5 μm or more (number / 5 .5 × 10 ⁻⁴ cm ³ ) or less may be used. If it exceeds 30, even if the titanium oxide is classified in the subsequent manufacturing process, it becomes difficult to make coarse particles of 1 μm or more 10% or less. Further, as a method for classifying titanium oxide, a method in which titanium oxide is made into an ethylene glycol slurry, and then coarse particles are centrifuged and separated by equipment such as a super decanter is preferable. The slurry to be classified can be stably classified when the titanium oxide concentration is low, and the amount of titanium oxide is preferably 20 g or less in 100 cc of the slurry. When the polymer is pelletized and further fiberized through the polymerization step, it is important to suppress secondary aggregation of titanium oxide, and it is preferable to shorten the time when the polymer is in a molten state as much as possible. Moreover, as long as it does not impair the object of the present invention, in addition to titanium oxide, it contains inorganic particles such as silica and alumina, organic pigments, antioxidants, anti-coloring agents, antistatic agents, light-proofing agents and the like in small amounts. May be.

  Within the scope of the present invention, the form of the monofilament is not particularly limited, and may be a composite monofilament made of two-component polyethylene terephthalate, for example, a core-sheath composite or bimetal composite, or a monofilament made of a single-component polyethylene terephthalate. However, in view of ease of yarn production and production cost, it is preferably made of a single component polyethylene terephthalate.

  Further, the screen filament monofilament of the present invention is required to have a strength of 5.6 to 6.2 cN / dtex and an elongation of 25 to 35%. The strength and elongation here refer to the strength and elongation at the breaking point in the tensile test. By setting the breaking strength to 5.6 cN / dtex or more, it is possible to obtain a high-strength and high-elasticity screen flaw, and it is possible to meet the required high printing accuracy. Moreover, by setting it to 6.2 cN / dtex or less, it becomes possible to suppress the shaving-like shaving at the time of weaving, which occurs when the yarn orientation is too high. A preferred strength range is 5.7 to 6.0 cN / dtex. Also, by setting the elongation to 25% or more, the passability in higher-order processes including weaving is improved, and by setting it to 35% or less, it is excellent that no wrinkle elongation occurs when a screen wrinkle is formed. Dimensional stability can be obtained. A preferable range of elongation at break is 27 to 33%.

  The present invention is described in detail below. In addition, the evaluation in an Example followed the following evaluation methods.

A. Intrinsic viscosity 0.10 g of monofilament was dissolved in 10 ml of orthochlorophenol and measured using an Ostwald viscometer at a temperature of 25 ° C.

B. Titanium oxide primary particle size distribution The obtained monofilament is dissolved in orthochlorophenol to obtain a solution, the concentration is adjusted so that the absorbance of the solution is in the range of 1.0 to 0.5, and the solution is prepared by CAPA- manufactured by HORIBA. Using 700, the particle size distribution was measured while centrifugal sedimentation. The measurement was performed at N = 10, and the average value of the abundance ratio (%) of primary particle sizes of 0.1 to 0.6 μm and 1.0 μm or more was determined.

C. Strength and elongation Using a Tensilon tensile tester manufactured by Toyo Baldwin, the value at the breaking point was determined from the stress-strain curve under the conditions of a test length of 20 cm and a tensile speed of 20 cm / min.

D. Measurement of Tomas dispersed coarse particle number 15.9 g of titanium oxide powder was put into 100 ml of ethylene glycol, shaken with a shaker for 30 minutes, and dispersed, and 2 drops were dropped onto a Toma blood cell board with a syringe. It was allowed to stand for 30 minutes, and the number of coarse particles of 5 μm or more was read. Measurement was performed at N = 5, and an average value was obtained.

E. Spinning property In obtaining a monofilament by the method of Examples described later, the yield of the monofilament obtained from 1000 kg of the chip raw material is 100% or less 95% or more ○○, less than 95% to 80% or more ○, less than 80% ～ 70% or more was evaluated as Δ, less than 70% as ×, and ◯ and ○ were regarded as acceptable.

F. Weaving property The obtained monofilament was made into a 300 mesh screen wrinkle with a slewer loom according to a conventional method, and evaluated by the number of scraping defects generated per 1 m ³ of the obtained screen wrinkle.

G. Comprehensive evaluation Each evaluation item was comprehensively judged and evaluated in four stages of XX, XX, △, and X, and XX and ◯ were regarded as acceptable.

Example 1
Mr. Thomas dispersed titanium oxide powder with 28 coarse particles in ethylene glycol to form a slurry with a titanium concentration of 20 g / 100 cc. The slurry was classified at a flow rate of 5.7 L / min in a super decanter, and finally In addition, an ethylene glycol slurry having a titanium oxide concentration of 15.9 g / 100 cc was obtained. Using this slurry, a polycondensation reaction was performed according to a conventional method to obtain polyethylene terephthalate pellets having an intrinsic viscosity of 0.78 and a titanium oxide content of 0.5% by weight. Subsequently, the pellet was melted and extruded at 300 ° C. with a pressure melter, guided to a spinning pack at a spinning temperature of 300 ° C. with a polymer passage time of 15 minutes, and the undrawn yarn was once wound at a speed of 800 m / min. Next, the unstretched yarn is stretched 4.4 times between the first hot roll having a surface temperature of 90 ° C. and the second hot roll having a surface temperature of 130 ° C., and then the cold roll having the same surface speed as that of the second hot roll. And then wound on a spindle to obtain a drawn yarn. The obtained drawn yarn has an intrinsic viscosity of 0.73, a fineness of 13 dtex, a strength of 5.9 cN / dtex, and an elongation of 30%. The contained titanium oxide has a primary particle diameter of 0% with 68% of the total number of particles. In the range of 0.1 to 0.6 μm, coarse particles having a primary particle diameter of 1.0 μm or more were 7%. There was no problem with the spinning performance, and the yield was 96%.

This monofilament was used for warp and weft, warped by a conventional method, and woven with a slewer loom to obtain a 300 mesh screen wrinkle. At this time, the process passability was very good, and no particular problem was found. As a result of inspecting the obtained woven fabric, the number of scraped defects was 0.028 pieces / m ³ and a good result was obtained.

Examples 2-3 and Comparative Examples 1-2
Except for using the same titanium oxide ethylene glycol slurry as in Example 1 and changing the polymerization degree of polyethylene terephthalate, Examples 2, 3 and 2 summarized in Tables 1 and 2 were used in exactly the same manner as in Example 1. The results of Comparative Examples 1 and 2 were obtained. In Comparative Example 2, the occurrence of shaving during weaving was very large.

Examples 4-5, Comparative Examples 3-4
Examples 4 and 5 and Comparative Examples 3 and 4 were the same as Example 1 except that the same titanium oxide ethylene glycol slurry as in Example 1 was used and the amount of titanium oxide added in polyethylene terephthalate was changed. The result was obtained. The results are summarized in Table 1 and Table 2.

Example 6 and Comparative Example 5
Example 6 was carried out in the same manner as in Example 1 except that the flow rate of the titanium oxide slurry to be treated with the superdecanter was 5.8 L / min, and Comparative Example 5 was 6.1 L / min. The results of Example 5 and Comparative Example 5 summarized in Table 2 were obtained. In Comparative Example 5, the particle size distribution was broader than that in Example 1, and the occurrence of abrasion during weaving was relatively large.

Example 7 and Comparative Example 6
In Example 7, Titanium dispersed coarse particle number 30 titanium oxide, Comparative Example 6 using Toma dispersed coarse particle number 45 titanium oxide, otherwise, in the same manner as in Example 1, The results of Example 7 and Comparative Example 6 summarized in Tables 1 and 2 were obtained. In Comparative Example 6, there was much shaving during weaving.

Example 8
Using the same titanium oxide slurry as in Example 1, polyethylene terephthalate pellets having a titanium oxide content of 0.5% by weight and intrinsic viscosities of 0.51 and 0.78 were obtained, and these were melted at 300 ° C. in a separate pressure melter. -Extruded and separately guided to a spinning pack at 300 ° C. and joined with a core-sheath type spinneret so that the core component has a high viscosity, the sheath component has a low viscosity polymer, and the core-sheath ratio = 8/2. The unstretched yarn of the core-sheath type composite monofilament was once wound up at a speed of minutes. Other than that was implemented by the method similar to Example 1, and the result of Example 8 of Table 1 was obtained. Although it was slightly inferior in spinning, the shaving property during weaving was good.

  The monofilament for screen wrinkles and screen wrinkles obtained by the method of the present invention have high strength and high elasticity, and can be preferably used for high-precision screen printing.

Claims (2)

  Titanium oxide having a particle size distribution in which 60% or more of the total number of particles has a primary particle size of 0.1 to 0.6 μm and particles having a primary particle size of 1.0 μm or more is 10% or less of the total number of particles. A monofilament for a screen wrinkle comprising polyethylene terephthalate containing 3 to 0.8% by weight, having a strength of 5.6 to 6.2 cN / dtex and an elongation of 25 to 35%.   The monofilament for a screen bag according to claim 1, comprising a single component of polyethylene terephthalate.