JPH0115622B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing animal hair-like fibers having a uniform and sharp tapered tip. Various natural animal hairs are currently widely used as materials for brushes, brushes, etc. However, natural animal hair is limited in quantity due to resources, and is not necessarily cheap. Therefore, various synthetic fibers, particularly polyester fibers, are being investigated as substitute materials for animal hair. Conventionally, a method is known in which the tips of polyester fibers are immersed in an aqueous alkaline solution to thin the tips, thereby obtaining polyester fibers that have a texture and appearance similar to animal hair. For example, Tokuko Sho 48-4910
The publication describes that a fabric using polyester fibers as a pile is treated by immersing the pile in an alkaline aqueous solution for a certain period of time from the tip of the pile to a specific length, and then raising the pile surface and immersing only the tip of the pile in an alkali solution. A method is described in which the tip of the pile is thinned by immersing it in an aqueous solution and treating it for a certain period of time. In this method, a step occurs at the boundary between the first-stage immersed section and the second-stage immersed section, and a tapered fiber with a gently tapered shape cannot be obtained.In addition, the tip shape is trapezoidal or semicircular. As a result, both the appearance and texture are inferior to animal hair. On the other hand, in order to eliminate this drawback, one end of a polyester fiber bundle having interfiber voids that can cause capillary action is immersed in an alkaline aqueous solution.
A method has been proposed in which polyester fibers are decomposed by an alkaline aqueous solution that rises through the fiber bundle due to capillary action to form a tapered tip, and the tip portion immersed in the alkaline aqueous solution is completely decomposed and removed. (Special Publication No. 50-40195). This method seems to produce a product with a sharp and uniformly tapered tip, and the tips are uniformly aligned without being treated to create unevenness in the longitudinal direction of the fibers. However, when actually implemented, it does not necessarily produce the expected effects. That is, when a fiber bundle is immersed in an alkaline aqueous solution, the fiber bundle expands in the outer circumferential direction, and a larger amount of the alkaline aqueous solution penetrates into the center, which causes more fibers to decompose in the center of the fiber bundle and shorten the fiber length. In addition, the fibers at the outermost periphery also tend to decompose and the length of the fibers becomes short, resulting in the end surface of the fiber bundle becoming uneven and the end portions not being uniformly aligned. In addition, if you try to completely decompose and remove the immersed part, the processing time will be longer, and further hydrolyzed monomers will float and adhere to the surface of the tapered tip of the fiber, reducing the smoothness of the tip. The problem of loss also arises. Another drawback is that it is relatively difficult to control the shape of the tip, such as the length of the tapered portion. In order to eliminate this drawback, the present inventors first immersed the tips of the polyester fibers in a hydrolysis bath for a certain length, and then gradually pulled up the polyester fibers continuously or lowered the liquid level of the hydrolysis bath. A method of continuous gradual reduction was proposed. However, in this method, there is a problem that a uniform tapered tip shape cannot be obtained unless the rate at which the polyester fiber is pulled up from the hydrolysis bath or the rate at which the liquid level in the hydrolysis bath decreases is strictly controlled. I understood. That is, if the pulling speed of the polyester fiber or the rate of drop in the liquid level is too low, the tip will not be gently tapered and will have an uneven shape, while if the speed is too high, the tip will become trapezoidal and sharp. I don't. In principle, it is easy to obtain animal hair-like fibers by immersing the tips of polyester fibers in a hydrolysis bath, but it is difficult to obtain animal hair-like fibers by using relatively thin polyester bristles with a fiber diameter of, for example, 0.10 mm or less. case,
The density of the fiber bundle becomes extremely high, and penetration of the hydrolyzate becomes extremely poor. Therefore, the temperature of the fibers located in the center of the fiber bundle away from the tip portion is difficult to increase, and the rate of thinning becomes extremely slow. Therefore, it was not possible to obtain a uniform product, and it was also difficult to obtain a sufficiently long taper length, which caused problems in terms of yield. As a method to solve the above-mentioned drawbacks, we have investigated various thinning conditions such as hydrolyzing agent concentration, hydrolysis temperature, hydrolysis time, method of immersing the fiber bundle in the hydrolysis bath, etc., but we have not been able to obtain satisfactory results. Ta. Therefore, many unresolved problems remain in mass production at an industrial level. As a result of intensive studies, the inventors of the present invention found that if the thinning process is performed while the temperature distribution within the fiber bundle is as narrow as possible, the difference in thinning speed between each part within the fiber bundle can be eliminated. I reached it. According to the present invention, the product obtained is extremely uniform, and even if fiber bundles made of relatively thin fibers with a fiber diameter of 0.10 mm or less and having a very high density are used, they are useful for writing brushes, painting brushes, etc. It has been found that animal hair-like fibers with a sufficiently long taper length can be obtained, and that the yield and workability are also good. That is, the configuration of the present invention is as follows. 1. When the tips of synthetic fibers are immersed in a hydrolysis bath to make them tapered, the synthetic fibers are bundled into a fiber bundle, and the temperature inside the fiber bundle before dipping satisfies the following formula (). After preheating,
This is a method for producing animal hair-like fibers, which is characterized by immersing the fibers in an aqueous solution containing a hydrolyzing agent. T _L ≧50 ……() [However, T _L is the center of the fiber bundle from the tip.
This is the temperature (°C) at a distance of 20 mm. ] Hereinafter, the present invention will be explained in detail. In the present invention, polyester fibers include ethylene glycol, trimethylene glycol, 1,4
- It is a polycondensate of glycol components such as butanediol and tetramethylene glycol and dicarboxylic acid components such as terephthalic acid, isophthalic acid, malonic acid, and succinic acid. A fiber made of a polyester polymer copolymerized with another third component as a part of a glycol component or a dicarboxylic acid component, or a blend of these polyester polymers and other polymers, and an aqueous solution of a hydrolyzing agent. It includes all polyester fibers that can be hydrolyzed by water, but polytetramethylene terephthalate fibers are most preferred because of their animal hair-like feel. It is preferable to use polyester fibers with a single filament fineness in the range of 20 to 200 DE in order to obtain animal hair-like fibers. If the single yarn fineness is too small, it will be difficult to obtain an animal hair-like feel, while if the single yarn fineness is too large, the yarn will become too rigid and its uses will be limited. Examples of hydrolyzing agents for polyester fibers include sodium hydroxide, potassium hydroxide, soda carbonate, and triethanolamine. These hydrolyzing agents are used in the form of a solution, and their concentration is not particularly limited and is appropriately selected depending on the type of polyester fiber to be treated, fineness, desired degree of fineness, and treatment bath temperature. In particular, it is preferable to heat an aqueous solution containing a hydrolyzing agent to treat the polyester fibers because the dissolution and decomposition rate of the polyester fibers increases and the treatment time can be shortened. The temperature of the processing liquid usually used is 70℃ to 130℃.
It is ℃. In addition, when using an alkali metal compound as a hydrolyzing agent, it is desirable to add a quaternary ammonium salt such as lauryldimethylbenzylammonium chloride or cetyldimethylbenzylammonium chloride, as this will accelerate the hydrolysis of polyester fibers. . The present invention performs tapering treatment while making the temperature of the fiber bundle as uniform as possible by preheating the temperature inside the fiber bundle of polyester fibers to a certain temperature or higher. The difference in the rate of hydrolysis between each part is made extremely small. In other words, in the conventional method, the temperature difference (temperature distribution) from the center to the periphery of the fiber bundle is extremely large, and the temperature of the center of the fiber bundle in particular does not rise easily even when immersed in an aqueous hydrolyzing agent solution. The problem was that it was difficult. As a result, the resulting product is non-uniform, especially in the case of relatively thin polyester fibers with a fiber diameter of 0.10 mm or less, the density of the fiber bundle is high and the permeability of the hydrolyzing agent aqueous solution into the fiber bundle is low. It has been extremely difficult to obtain animal hair-like fibers with a sufficiently long taper length. Therefore, as a result of intensive study, the present inventors determined that the temperature inside the fiber bundle before the tapering treatment should be set to 50°C or higher, preferably
It was discovered that if the tapering treatment is performed after preheating to 70°C or higher, the difference in tapering speed between the inner and outer layers within the fiber bundle becomes extremely small, resulting in uniform animal hair-like fibers with a sufficiently long taper length. Ta. Here, the temperature inside the fiber bundle is the temperature at the center of the fiber bundle at a position 20 mm away from the tip. In other words, if the temperature inside the fiber bundle is less than 50℃,
As a result, even within the same fiber bundle, there is a temperature difference of 30°C or more between the tip end near the hydrolysis bath and the center of the fiber bundle away from the hydrolysis bath when the fibers begin to thin. There is also a difference in the behavior of temperature rise within the fiber bundle after the start of thinning.The tip of the fiber bundle, which is close to the hydrolysis bath, is easily heated, but the center of the fiber bundle, which is away from the hydrolysis bath, is It takes an extremely long time to heat up compared to the tip. Therefore, the difference in thinning speed within the fiber bundle becomes extremely large, and even if the thinning processing conditions are variously changed, it is not possible to obtain animal hair-like fibers that are uniform and have a long taper length. On the other hand, the temperature inside the fiber bundle is
The above-mentioned drawbacks can be overcome by performing a thinning treatment after raising the temperature to 50° C. or higher, preferably 70° C. or higher. That is, the reaction can be started in a state where the temperature difference between the tip of the fiber bundle near the hydrolysis bath and the center of the fiber bundle at a position away from the hydrolysis bath is small. Furthermore, the subsequent temperature rise in the center of the fiber bundle located away from the hydrolysis bath is also relatively quick.
Therefore, the difference in thinning speed between each part within the fiber bundle becomes extremely small, and the resulting animal hair-like fibers are uniform and have a sufficiently long taper length. This is a method of increasing the temperature inside the fiber bundle, but a simple method is to keep the fiber bundle above the liquid level of the hydrolysis bath and heat it with steam from the hydrolysis bath before the thinning treatment.
Moreover, the effect is sufficiently large. Although the degree of temperature rise is
Desired conditions can be set by changing the distance between the fiber bundle and the hydrolysis liquid surface or the time the fiber bundle is held on the liquid surface.In particular, if the hydrolysis bath is sealed with a lid etc., the effect will be improved. It becomes even bigger. To measure the temperature of the fiber bundle, a temperature detection end was embedded in a predetermined position from the tip of the fiber bundle in the center, and the temperature at that position was measured over time. Another method is to preheat the fiber bundle and then immerse it in a hydrolysis bath to make it thin. , this purpose can be achieved. The thickness and taper length of the fibers were measured by enlarging the polyester fibers 100 times using a Nippon Kogaku universal projector (Nikon 6C2). More specific examples will be given below. Example: Polytetramethylene terephthalate with an intrinsic viscosity of 1.0 is melt-spun and then stretched to obtain a single fiber fineness.
A bristle fiber of 50 de was obtained. These bristle fibers were bundled to create a fiber bundle with a diameter of 45 mm and a length of 50 mm. This fiber bundle was processed using the apparatus shown in FIG. FIG. 1 is a longitudinal sectional view showing an example of an apparatus used for carrying out the present invention. Here, 1 is a treatment bath, 2 is a thinning treatment bath, 3 is a tape that ties and fixes the fiber bundle, 4 is a fiber bundle, 5 is a wire that raises and lowers the fiber bundle, 6 is a motor, and 7 is a roller. The treatment liquid contains 25% by weight of sodium hydroxide.
An aqueous solution at 107°C was used. In order to accelerate the reaction, the fiber bundle was treated with lauryl trimethylammonium chloride 15, which is a quaternary ammonium salt.
% aqueous solution. Before being immersed in the treatment liquid, the fiber bundle was placed at a position 3 mm above the treatment liquid, preheated with steam from the treatment liquid, and then immersed in the treatment liquid. The standing time is 5 minutes, 10 minutes, 15 minutes, 30 minutes, and 40 minutes.
I did the standard. Table 1 shows the temperature distribution within the fiber bundle at each level.

【table】

[Table] As shown above, when the standing time is short, the temperature at the center of the fiber bundle is low and the temperature difference △T within the fiber bundle
It's also big. Immediately after preheating, the above samples (Nos. (1) to (5)) were immersed in a treatment bath for 35 mm and left for 35 minutes.
Table 1 shows the temperature inside the fiber bundle while it is immersed in the treatment bath.

[Table] For Nos. (1) and (2) with short preheating times, the temperature rise at the center of the fiber bundle during hydrolysis is slow, and the temperature difference between it and the tip is large. On the other hand, for Nos. (3) and (4), the temperature at the center of the fiber bundle rose extremely quickly, and the temperature difference between it and the tip was extremely small. The aforementioned samples (1) to (5) were taken out from the treatment bath and washed with water to remove residues attached to the fibers. Next, the fiber bundle is squeezed, drained, and placed in the treatment bath again.
It was immersed for 35 mm and pulled up continuously for 30 minutes at a speed of 1.17 mm per minute. The fiber bundle was taken out from the treatment bath, washed with water, and dried. Table 1 shows the morphology of the obtained fibers.

[Table] The morphology of the obtained animal hair-like fibers is defined as follows. Γ Taper form ×: Taper length at the tip of the fiber bundle is smaller than 10 mm. Δ: Taper length at the tip of the fiber bundle is 10 to 15 mm. ○: The taper length of the fibers at the center of the fiber bundle is greater than 15 mm. Γ Tip form ○: The tip is completely pointed and has a soft touch. Δ: The tips were not completely sharpened to some extent, and had a rough and hard touch. Γ Difference between the center and the outer periphery ○: The difference between the center and the outer periphery of the fiber bundle is extremely small in both the taper form and the tip form. Δ: The outer peripheral part of the fiber bundle has a taper length of 15 mm or more, but the tapered length in the center part of the fiber bundle is 10 to 15 mm. Γ Length variation ○: No unevenness at the tip of the fiber bundle. Δ: Some unevenness is present at the tip of the fiber bundle. As described above, by preheating the inside of the fiber bundle to a temperature of 50° C. or higher and then performing the thinning treatment, it was possible to obtain animal hair-like fibers with a sharp taper at the tip of the fiber bundle and excellent quality. Comparative Example A fiber bundle was immersed in a treatment bath for 35 mm without preheating, and a thinning treatment was performed for 35 minutes. Table 1 shows the temperature inside the fiber bundle during dipping.

[Table] The above samples were subsequently treated in the same manner as in the examples to obtain animal hair-like fibers. Table 1 shows the morphology of the animal hair-like fibers obtained.

[Table] Unless the fiber bundle is preheated, it is not possible to produce a fiber bundle with a sharp taper. Moreover, the quality of the animal hair-like fiber is also low.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an example of an apparatus used to carry out the present invention.

Claims (1)

[Scope of Claims] 1. When the tips of synthetic fibers are immersed in an aqueous solution of a hydrolyzing agent to make them tapered, the synthetic fibers are bundled into a fiber bundle, and the temperature inside the fiber bundle before dipping is set as follows. After preheating to satisfy formula (),
A method for producing animal hair-like fibers, which comprises immersing them in an aqueous solution of a hydrolyzing agent. T _L ≧50 ...() [However, T _L is the temperature (°C) at the center of the fiber bundle, 20 mm away from the tip of the fiber bundle. ]