JPS6328036B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a felt-tip pen core. Traditionally, recycled acetate fibers have been mainly used as the fibers used in cores for felt-tip pens, but with the diversification of inks used in recent years, some types of solvents have caused the fibers to dissolve or dissolve. It was recognized that the ink had serious drawbacks, such as not being able to be used as an ink, or causing color changes due to selective absorption of pigments in the ink over time. For this reason, research has been carried out on alternative fiber materials with excellent chemical resistance, but it has been found that these drawbacks can be overcome by using fibers obtained by melt spinning such as polyester and polyolefin fibers. There was found. Among these, polyester synthetic fibers in particular have been able to gradually expand in quantity because their quality, price, etc. are stable and extremely excellent. However, the polyester-based synthetic fibers that have been put on the market for felt-tip pen cores are made by applying staples to cards and making them into slivers, and although the fibers themselves have excellent physical properties, there are slight variations in the sliver manufacturing conditions. Immediately, this appeared as spots in the product's characteristics, such as ink absorption, and as a result, it was pointed out that it was difficult to use it in high-end felt-tip pens, etc., which required extremely uniform characteristics. The present inventors considered these points and found that it was necessary to change the conventional sliver to a tow-like material in order to take advantage of the characteristics of polyester fiber and further improve the uniformity that had been a problem in the past. I thought there was. By the way, felt-tip pen cores using acetate tow have already been put to practical use, but it has been quite difficult to make felt-tip pen cores using polyester tow. The reason for this is thought to be that there are basically large differences in rigidity, surface properties, crimp characteristics, etc. between polyester and acetate. Therefore, the present inventors conducted intensive studies on the factors necessary to make these differences equal or higher than the final quality, and as a result, they arrived at the present invention. That is, the present invention has 18 to 30 crimps/
in, single yarn denier (hereinafter abbreviated as dr) is 5 to 7
A continuous organic synthetic resin fiber with a density of 0.12
~0.27g/cm ³ , maximum swelling amount of water-based ink is 0.8
This is a core for a felt-tip pen that was bundle-molded as described above. Conventional cores for felt-tip pens using acetate tow have a maximum number of crimps of about 15 to 17 crimps/in, and a single thread denier of up to about 4 dr. Thick denier ones were not used practically. Nevertheless, when polyester is used, it has not been possible to obtain sufficient quality with crimp and denier comparable to conventional acetate. The reasons for this include, as mentioned above, polyester is much more rigid and crimped, and the surface is smooth due to melt spinning (acetate is porous). It is presumed that this is due to the difference in the uniformity of crimp and the physical properties of the ink. In addition, normal polyester fibers have a crimp count of around 10 pcs/in, which is higher than that of acetate, and the single yarn denier is also higher than that of acetate.
Although it is impossible to use inks larger than 4dr as they are for felt-tip pen cores, inks with a crimp count of 18 crimps/in or more, which exceeds the common sense of acetate, have good ink physical properties. It was completely unexpected that it was suitable as a core for felt-tip pens. That is, when using polyester tow,
Even with a single yarn denier of 5 dr and a crimp count of 15 to 17 strands/in, which is comparable to acetate, it was not possible to obtain sufficient quality as a core for felt-tip pens. In, preferably 20 to 25 pieces/inch, a good core for felt-tip pens could be obtained. Even if the number of crimps is increased to the conventional 10 crimps/in or 15 to 17 crimps/in, the tow does not have elasticity or elasticity during opening during forming the felt-tip pen core, and the opening method described below The fibers cannot be opened properly, causing uneven opening, or there may be a situation where the fibers have no elasticity and cannot be opened. In addition, in terms of performance as felt-tip pen cores, those with these numbers of crimps have disadvantages in that the maximum content is small and there is a lot of dropout. However, it was found that acetate with a crimp count of 18 to 30 crimps/in, which exceeds the common knowledge of conventional acetate, has good opening properties and good ink retention properties. Especially when the number of crimps is 20~
Those in the range of 25 pores/in exhibit excellent ink retention properties. If the number of crimps exceeds 30 crimps/in, the tow will exhibit a hardening phenomenon and will become difficult to open. As a result, drawbacks such as poor ink retention were observed. In order to obtain the number of crimps as mentioned above, the thickness coefficient of the tow before crimping must be set at 10,000 to 50,000 dr/
cm, preferably 15,000 to 28,000 dr/cm. Such a thickness coefficient is lower than the conventional empirically known value of 50,000 to 70,000 dr/cm. It is therefore desirable that much thinner tow be used. When opening tow-like materials, those with a tow thickness coefficient of 50,000 dr/cm or more, that is, those with a tow thickness that has been conventionally used, may not be opened depending on the method of opening by elongation. If the fibers are not sufficiently fibered and unevenness occurs and the pen core is used,
This poses the problem of affecting ink retention characteristics such as maximum ink content. In addition, if it is less than 10,000 dr/cm, it is difficult to provide crimp suitable for the use of the present invention. With such a thin tow, it is possible to spread the fibers uniformly and to obtain excellent physical properties in terms of ink retention properties. For fiber opening, it is not possible to spread the fibers properly by simply stretching the tow in the lateral direction. That is, in order to open the tow, tension is applied so that the tow has an apparent length of 1.5 times or more (50% or more) of its original length, preferably 1.7 to 50%.
By applying tension to 2.0 times the tension and then removing the tension (preferably applying an overfeed of 10 to 20% or more), the phase of crimp is shifted, and the toe width is about 20 to 60 mm. 250～
This refers to the operation of widening to about 330mm. Here, if the tension is such that the length of the tow is only 1.5 times or less, the tow cannot be opened properly, and it becomes difficult to apply resin during resin processing, which is performed as necessary. This resin processing is carried out for the purpose of uniform ink retention characteristics and the like. On the other hand, if you apply too much tension, the tow will stretch too much and fuzz will appear, so be careful. In order to impart extensibility to the tow, it is desirable that the secondary crimp is further at a predetermined value. The number is 3 pieces/in
Below, good results can be obtained especially when the amount is about 0.5 to 1.5 pieces/in. If such crimps are too strong, the shape after opening will be poor, so it is desirable that the crimps remain to a certain extent during the opening process. Therefore, crimping should be done so that the crimp fastness is not too high. A suitable fastness is 12% or less, preferably about 9 to 5%. By the way, the performance of a felt-tip pen is that it can write a lot of characters (character runnability), ink drips,
An important point is that there is no dripping. Therefore, if the gap in the core is too small, the amount of ink that can be put into the gap will be small, making it difficult to write many characters and shortening the life of the felt-tip pen.If the gap is too large, too much ink will get in, causing smearing or The drop-off phenomenon occurs,
This is a fatal flaw as a felt-tip pen. Character runnability, ink smearing, etc. of these felt-tip pens can be expressed in terms of the maximum amount of water-based ink contained per gap and the ink absorption rate. As a result of careful consideration of these points, we found that the density of the fiber bundle as a core is 0.12 to 0.27 g/cm ³ (porosity 80.5 to 91.5%).
Moreover, it was found that it is extremely difficult to make the maximum content of water-based ink per void equal to or greater than 0.8. In addition, the ink wicking rate is an indicator of the basic ink suction power of the core.
If this value is small, the ink retention performance will be insufficient, so it has been recognized that the aqueous ink absorption rate must be at least 60%, preferably 70% or more. All of these are 25℃65%
Measure in RH. If the density is less than 0.12 g/cm ³ , the maximum ink swell will increase, but it will tend to drip, which is not practical, and if the density is 0.27 g/cm ³ or more, the maximum ink swell will increase. The disadvantage is that the number of characters decreases, many characters cannot be written, and the lifespan of a felt-tip pen is short. Furthermore, even if the density is within the above specification, if the fiber bundle is bundled in a state where there is a difference in density between high and low in some parts, that is, the density is uneven, the maximum swelling amount of the ink will vary due to the reasons mentioned above. Therefore, it is necessary for both to satisfy the range specified in the present application. As described above, in the present invention, the single yarn denier is required to be within the range of 5 to 7 dr. If the denier is smaller than this, it is difficult to obtain a sufficient opening state as a tow, resulting in uneven ink properties, and it is difficult to perform resin processing, etc., if necessary. If it is too thick, the opening state is good, but the ink properties are insufficient, and undesirable phenomena such as droplets occur due to a decrease in ink retention ability, for example. Conventionally, it can be inferred from the capillary phenomenon theory that the smaller the yarn withdrawal denier, the better the ink wicking ability will be. However, contrary to expectations, even if the material has a larger denier than acetate, if it is given a very large number of crimps and/or has specific surface properties as described below, it has an extremely excellent ink retention ability. It was discovered that core for felt-tip pens can be obtained. These things were unexpected from the conventional knowledge of acetate tow. Furthermore, as a result of examining the ink retention properties of cores for felt-tip pens, we found that substantially no surface treatment agent adhered to the surface of the polyester fibers (the electrical conductivity of the tow surface is 1 x 10 ⁹ Ω or more, preferably 1×
10 ¹⁰ Ω or more) exhibits better ink properties than those to which a hydrophilic surface treatment agent is attached (despite the fact that the ink in this case is a water-based ink). At the same time, when polyester fibers with a single filament denier of 5 to 7 dr and on which the surface treatment agent is not substantially attached are stretched and opened in the manner described above, the electrical conductivity is 0 ± 2 KV, preferably 0 ± 5 KV. It has been found that it is preferable to spread the fibers while being charged so as to be outside the range of . By opening the fibers in this way, the tow spreads more uniformly and more fully when the fibers are opened, making it easier to perform resin processing if necessary, and providing better ink performance as a core for felt-tip pens. You can get something with . In addition, here, fibers with virtually no surface treatment agent attached to the fiber surfaces (the electrical conductivity of the tow surface is 1
×10 ⁹ Ω or more, preferably 1 × 10 ¹⁰ Ω or more)
It is preferable to use Conventionally, the electrical conductivity of the tow surface was 1×10 ⁷ to 1
It is within the range of ×10 ⁹ Ω, and the surface treatment agent is applied with sufficient consideration given to electrostatic problems.
In other words, it has been found that even if the oil has an affinity for ink, it does not necessarily give good results to the physical properties of the ink. For this purpose, it has been found that good ink physical properties can be obtained by reducing the amount of the surface treatment agent so that the electrical conductivity of the fiber surface is 1×10 ⁹ Ω or more, preferably 1×10 ¹⁰ Ω or more.
These physical properties of ink were applicable to both water-based and oil-based inks. In the present invention, the organic synthetic resin fibers include:
There are various types of fibers such as polyethylene, polypropylene, polyamide, aromatic polyamide, polyvinyl chloride, and polyester fibers, but they have chemical resistance, ink resistance,
Considering cost resistance, etc., polypropylene-based or especially polyester-based synthetic fibers are considered to be the best. Polyester synthetic fibers refer to aromatic polyesters made of terephthalic acid, aliphatic diols having 2 to 4 carbon atoms, 1.4 hexamethylene dimethanol, naphthalene dicarboxylic acid, and composite fibers or blended fibers thereof. Furthermore, it also includes those copolymerized with 20 mol% or less of a third component. Copolymerization components include aromatic dicarboxylic acids such as isophthalic acid, naphthalene dicarboxylic acid, and sulfoisophthalic acid, oxycarboxylic acids such as P-oxybenzoic acid and P-β-oxyethoxybenzoic acid, and alicyclic acids such as cyclohexanedicarboxylic acid. Conventionally known compounds include dicarboxylic acids, aliphatic diols such as 1.3 propane diol, 1.6 hexane diol, and neopentyl glycol, pentaerythritol, polyethylene glycol, polybutylene glycol, and methoxypolyethylene glycol. In addition, these polyester synthetic fibers contain additives commonly used in the past, such as titanium compounds, silica compounds, phosphorus compounds, metal compounds used as catalysts, flame retardants, antistatic agents, pigments, and other reaction inhibitors. may be included. Among the polyester fibers mentioned above, polyethylene terephthalate is the most preferred in terms of quality and price. Various cross-sections of the single fibers used here are used, such as round, T-shaped, U-shaped, Y-shaped, hollow, and hollow irregular shapes, but from the viewpoint of bulk, hollow or U-shaped cross sections are effective. It is. The form of crimp may be either mechanical crimp or coil crimp, but mechanical crimp is simpler. Coil crimp is obtained by stretching fibers obtained by a rapid cooling method, an asymmetric method, a conjugate method, an air jet method, etc. and then causing the fibers to become crimped. Mechanical crimp methods include the stuffing box method and the gear method, among which the stuffing box method is the most suitable. The number of crimps in the text refers to the number of crimps taken from each part of the test at random, and when a load of 2 mg per denier is applied to each fiber, the crests and troughs between 1 inch are counted and divided by 2. This is the number of ivy. The thickness coefficient is the toe denier (10,000 dr) divided by the roller width (cm) of the stuffing box crimper. Water-based ink is a commercially available product that is generally used in water-based felt-tip pens. There is not that much difference between the quality of each company. The maximum content amount corresponds to the amount of saturated ink that occupies the void volume when forming a core for a felt-tip pen, and ink is injected from the top of the vertically erected core, and the ink begins to fall from the bottom. It can be calculated from the amount of input up to. The ink wicking rate is calculated by immersing the lower end of the core in 5 mm of ink, measuring the amount of ink sucked up by the capillary phenomenon for 3 minutes, and dividing the amount by the maximum swelling amount and expressing it as a percentage. The present invention will be explained below with reference to Examples, but the present invention is not limited thereto. Example 1 Polyethylene terephthalate was synthesized by a conventional method and spun to obtain a raw fiber having a hollow cross-section with [η] 0.62 (phenol:tetrachloroethane=1:1, measured at 30°C). After converging, it was stretched in two stages at a stretching speed of 60 m/min in a hot water bath at 85 to 95°C, and then a treatment agent (octyl phosphate K salt) was applied.
Tows with a single yarn denier of 6.2 dr and a total denier of 50,000 dr were obtained with various crimp numbers from 14 to 24 crimps/in. The thickness coefficient was 21,000 dr/cm. A core for a felt-tip pen of 6.4φ x 84 m/m was prepared by performing roller opening with stretching and tension removal operations and wrapping the outer layer with cellophane. Table 1 shows the composition and ink characteristics of each core.
Shown below. As a result, the ink of the present invention showed superior ink properties compared to the control.

[Table] Example 2 Polyethylene terephthalate was synthesized by the usual method and spun to produce raw material with a hollow or solid round cross-section at [η] 0.64 (phenol:tetrachloroethane=1:1, measured at 30°C). Got the thread. After converging, stretch in a hot water bath at 85 to 95℃ for 2 hours at a stretching speed of 85 m/min.
Thickness coefficient without step stretching and surface treatment agent
Multiplying the crimp number of 18 to 21 crimps/in at 15,000 dr/cm, we obtained tows with a total denier of 40,000 dr for single yarn deniers of 3 dr, 5 dr, 6 dr, and 10 dr. Stretch these toes -
Roller opening with tension removal operation is performed,
The outer layer was wrapped with cellophane to create a felt-tip pen core measuring 5.6φ x 80m/m. As a result, it was found that the thicker the dr was, the better the results were for the fibers with good spreadability without uneven fiber opening, while the 3 dr fibers had a large amount of unspreaded fibers and were found to be problematic for making felt-tip pen leads.
In addition, the ink properties of the 10 dr ink were poor, with some smearing in the ink (see Table 2).

[Table] Example 3 Polyethylene terephthalate synthesized by a conventional method was spun to obtain a raw fiber with a hollow cross-sectional shape of [η] 0.62. After converging, it was stretched in two stages at a stretching speed of 60 m/min in a hot water bath at 85 to 95°C, and the thickness coefficient was 22,000 dr. /cm crimped, single yarn denier 5.6 dr, total denier 62,000 dr
obtained a tow. These tows were stretched and opened, and the outer layer was wrapped with cellophane to prepare a felt-tip pen core of 7.0φ x 84 m/m, and the results shown in Table 3 regarding the ink properties were obtained. That is, it was found that the polyester fibers to which no surface treatment agent was applied not only showed excellent fiber opening properties but also had very superior ink properties compared to the control fibers.

【table】

Claims (1)

[Claims] 1 Number of crimp: 18~30 pcs/in, single yarn denier: 5~
Continuous organic synthetic resin fibers with a density of 7.
0.12~0.27g/cm ³ , the maximum swelling amount of water-based ink is
A core for felt-tip pens that is bundled and molded to have a diameter of 0.8 or higher.