JPH0352963B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a monofilament for hair brushes that has excellent electrical conductivity. Conventionally, in the field of textiles for clothing and carpets, much research and development has been carried out on conductive fibers in order to overcome the adverse effects caused by static electricity, and various results have been achieved. For example, various conductive substances such as metals, carbon black, cuprous iodide, and tin oxide have been studied as conductive substances to be added to fiber materials, and methods for introducing these conductive substances into fibers have also been investigated. Various methods have been proposed, such as a method of kneading the fibers and a method of introducing the fibers into a part of the fibers by composite spinning. On the other hand, the wire diameter of hair brushes, industrial brushes, etc.
In the field of monofilaments over 400μ,
Similarly, there is the problem of static electricity, which is often experienced with hairbrushes, and when brushing hair in an overly dry state after washing, static electricity is generated, resulting in poor hair styling. In order to improve these drawbacks of hair brush bristle materials, measures have been taken in the past, such as introducing hydrophilic polymers such as polyalkylene glycol, but they are not effective in dry conditions and low humidity. However, only insufficient results were obtained. Monofilaments whose surface was coated with a substance containing a conductive substance were also attempted, but these had insufficient abrasion resistance and were not durable. Furthermore, monofilament for brushes with a layer containing conductive carbon formed by composite spinning is expected to have the effect of improving conductivity, but conventionally it has been difficult to develop this type of bristle material for hairbrushes for the following reasons. It was thought that In other words, conductive yarns for clothing and carpets generally have a single yarn fineness of at most 50 denier, and the winding speed during air cooling and solidification after spinning from the spinneret to winding is typical. Since the cooling speed is faster than that of monofilament, the time required for cooling and solidification is shorter than that of monofilament, but cooling progresses gradually. On the other hand, in the case of monofilaments with a diameter of 400 μm or more, after spinning, the method is generally to cool them by passing them through cold water, hot water, or a liquid refrigerant bath. Even if a polymer is used, it is a rapid cooling from the viewpoint of the melting temperature of the polymer. Monofilament yarns have a large diameter, so if you want to maintain the circularity and uniformity of the diameter of the undrawn yarn, it will not be able to cool down easily with slow cooling, and the molten polymer will be discharged from the spinneret. Such an emergency step is necessary to balance the falling speed and take-up speed of the yarn, and rapid cooling and solidification can suppress the molecular orientation of the undrawn yarn. It can improve your sexuality. Therefore, when attempting to obtain a conductive monofilament by composite spinning using conductive carbon black as a conductive substance, due to the above-mentioned spinning process and the difference in the thickness of the yarn to be spun, it is difficult to produce a monofilament for clothing or carpets. Several issues that were not a problem in the fine denier yarn spinning process become obstacles. One example is the different shrinkage behavior of thermoplastic polymers containing conductive carbon black and thermoplastic polymers without conductive carbon black during the cooling and solidification process. This is due to the large contraction of the layer containing conductive carbon black, and although it depends on the introduction position of this layer and the thickness of the layer, it is said that as a result, the roundness of the monofilament deteriorates and it becomes flattened. This causes problems in terms of physical properties and quality of the product. As an example, regardless of whether it is a net denier yarn made by air-cooled spinning or a monofilament made by water-cooled spinning,
It is generally recognized that drawing destroys the chain structure of carbon black and reduces its conductivity, but in the case of monofilament, unlike fine denier yarn, the thickness of the conductive carbon black-containing layer also decreases. There is inevitably a large difference in stretchability between the part and the part that does not contain conductive carbon black. In other words, with fine denier yarn, the heat during drawing spreads relatively uniformly in a short period of time, making it easier to draw uniformly, whereas in the case of monofilament, the portions that do not contain conductive carbon black have clear netting. Although the conductive carbon black-containing layer is stretched with a point, there is a noticeable difference in that the necking point is difficult to determine, and the cutting of the chain structure of the conductive carbon black is caused by the thin denier yarn. This is considered to occur more frequently than in other cases. As a result of various studies aimed at improving the problems of the above-mentioned conductive monofilament, the present inventors have determined that the thickness ratio of each layer of a conductive monofilament having a core-sheath structure and having a layer containing conductive carbon black. By specifying the wire diameter, we succeeded in efficient manufacturing, and when used as a bristle material for a hairbrush, we were able to obtain a conductive brush with no problems in terms of physical properties and durability. We discovered that this can be done, and were able to arrive at the present invention. That is, the present invention combines a polyamide (A) containing conductive carbon black and a polyamide (B) which essentially does not contain conductive carbon black with the polyamide (A) containing conductive carbon black.
The layer has a triple core-sheath structure (X>0 in the formula below) or a double core-sheath structure (X=0 in the formula below).
), the wire diameter D arranged to become the sheath layer is
A concentric core-sheath composite monofilament of 400μ or more, in which the thickness of the outermost layer essentially consisting of the above polyamide B is x (μ), and the thickness of the intermediate layer consisting of the above polyamide A is y (μ), the monofilament The wire diameter is D
(μ), it has a cross-sectional shape that satisfies the following and the formula at the same time, and has a volume resistivity of 10 ⁸
The present invention provides a bristle material for a hairbrush characterized by being made of a composite monofilament having a resistance of Ω·cm or less. D−2x−√4 ² −4+0.98 ² ≦2y≦D −2x−4 ² −4+0.7 ² ... 0≦x≦50 ... In the present invention, polycapropylene is used as polyamide (A) and (B). It is preferable to use at least one selected from amide, polyhexamethylene adipamide, and polyhexamethylene sebamide.
It is preferable that the polymers (A) and (B) are of the same type, but good results can be obtained even when they are of different types, such as when (A) is polycaproamide and (B) is polyhexamethylene adipamide. can get. The conductive carbon black used in the present invention can be arbitrarily selected from carbon blacks commonly used in conductive resin compositions, such as acetylene black, furnace black, and channel black. Further, the amount of conductive carbon black to be blended varies depending on the type of carbon black used. For example, in the case of acetylene black, it is 20 to 55% by weight, preferably 25 to 55% by weight, based on the polyamide resin.
35% by weight, and in the case of furnace blacks, from 5 to 38% by weight, preferably from 10 to 35% by weight, based on the polyamide resin. These appropriate ranges also vary depending on the particle size of carbon black; generally, if the particle size is small and the surface area is large, a relatively low amount is sufficient, and if the particle size is large, a relatively high amount is required. is necessary. Generally speaking, when focusing only on conductivity, it is most preferable to have a layer containing conductive carbon black on the fiber surface. However, in the case of monofilament, as mentioned above, it is difficult to introduce a layer containing conductive carbon black into a certain part of the yarn cross section because of the deformation of the cross-sectional shape of the yarn due to the difference in shrinkage rate of each layer during cooling and solidification. is not preferable, requires a concentric core-sheath structure, and requires consideration of uniformity of layer thickness. Therefore, among the core-sheath composite structures, the double-core-sheath structure with a layer containing conductive carbon black as a sheath component is superior from the point of view of conductivity, but the durability of the conductive layer is From this point of view, a triple core-sheath structure in which a layer containing conductive carbon black is disposed as an intermediate layer is more advantageous. In the present invention, the thickness and position of the layer containing conductive carbon black and the concentration of conductive carbon black can be set as appropriate.
In the case of ~55% by weight polyamide (A), the inventors investigated the thickness and position of the layer, and found that conductivity and sufficient physical properties can be achieved only when the cross-sectional shape satisfies the following relational expression: It has been found that a product with high durability and durability can be obtained. D−2x−√4 ² −4+0.98 ² ≦2y≦D −2x−4 ² −4+0.7 ² …… 0≦x≦50 …… Here, x essentially does not contain conductive carbon black The outermost layer made of polyamide (B) and its thickness (μ) y is the thickness (μ) of the middle layer made of polyamide containing conductive carbon black D is the wire diameter (μ) of the brush bristle material, 400μ
The above range is shown. In the case of 2y<D-2x-√4 ² -4+0.98 ² , the uniformity of the thickness of the conductive carbon black-containing layer becomes poor, and at the same time, the conductive performance is insufficient. Also, if 2y>D−2x−√4 ² −4+0.7 ² ,
Not only do disadvantages such as poor stretchability during spinning, collapse of the cross-sectional shape, and deterioration of physical properties occur, but the conductivity reaches saturation, and as the thickness of the conductive layer increases, no improvement in conductivity is observed. Furthermore, in the case of x>50, it is preferable from the viewpoint of conductive performance that 0≦x≦
It is a good idea to keep it within the range of 50. For example, if a monofilament with a diameter of 0.55 mm is coated with a furnace black 30
In double core-sheath structure yarns in which polyamide containing % is introduced as a conductive layer, the thickness of the layer containing conductive carbon black must be at least 0.005 mm or more from the point of view of uniformity of layer thickness. From the viewpoint of conductivity, a thickness of 0.015 mm or less was sufficient. Also,
The results show that the diameter is preferably 0.040 mm or less since the spinning conditions are constrained from the viewpoint of the physical properties of the thread. These values naturally differ depending on the diameter of the monofilament, the content of conductive carbon black, etc. An important point that must be kept in mind in order to obtain the conductive monofilament according to the present invention is the method of cooling the molten polymer discharged from the die. It is necessary to reduce the shrinkage of the conductive carbon black-containing layer due to rapid cooling while maintaining roundness. Depending on the discharge amount, take-up speed, and desired thread thickness,
Although the conditions differ each time, it is important to choose a gradual cooling method as long as it is permissible. It can be adjusted by adjusting the temperature of the discharged material, the distance it enters the cooling medium, the immersion length of the cooling medium temperature, etc. In some cases, it may be necessary to provide a heat insulating cylinder or the like and auxiliary heating means directly below the cap. In addition, in order to suppress structural destruction of the conductive carbon black during stretching, the degree of polymerization of polyamide A used to knead the conductive carbon black is adjusted to adjust the melt viscosity, and the molecular It is appropriate to adjust the ease of plastic deformation. This is also affected by the type and amount of carbon black to be kneaded. The thus obtained hair brush bristle material of the present invention has excellent spinning properties (stretchability), cross-sectional shape (roundness), and physical properties (electrical conductivity, strength and elongation properties), making it ideal as a hair brush bristle material. It has excellent performance. Hereinafter, specific embodiments of the present invention will be described by way of examples. Example 1 35% by weight of conductive furnace black was mixed with sulfuric acid polycaproamide with a relative viscosity of 2.6, melt-kneaded using a twin-screw extruder, and then pelletized to obtain component A. Using polyhexamethylene diamine having a relative viscosity of 3.0 as component B, a double core-sheath composite monofilament having component A as a sheath and component B as a core and having a diameter of 0.57 mm was obtained by a conventional composite spinning method. By adjusting the extrusion amount of component A and component B, component A and layer thickness y derived from the above formula in the final monofilament are 50 and 50, respectively.
47, 40, 7.2, and 2.9μ (in this case, x=0 and D=570 in the equation). The melting temperature of component A was set at 280°C, the melting temperature of component B was set at 285°C, and the temperature of the composite mouthpiece was set at 283°C. After discharging from the composite nozzle, a 10 cm long heat insulating tube was placed directly below the nozzle, and the thread passage temperature inside the heat insulating tube was set at 200°C. The film was introduced into a 70°C hot water bath located 5 cm below the heat-insulating cylinder, then taken off with a take-up roller, and then stretched in two stages to 4.5 times using a hot water stretching tank. The first-stage stretching temperature was 75°C, and the second-stage stretching temperature was 83°C. on the other hand,
A single yarn using only component B without any conductive layer (component A) was produced on a separate spinning machine. The spinning conditions were the same as those described above. A plurality of the six levels of monofilament drawn yarn thus obtained were drawn together and continuously guided into a dry heat tank with a length of 6 m at a speed of 8 m/min, heat set for straightening, and made into hair brushes. Made of wool. At this time, the temperature inside the tank was 200°C.
The volume resistivity and physical properties of the obtained monofilament are shown in Table 1, and the conditions during spinning are also noted. Note that a Kyokucho insulation meter manufactured by Toa Denpa Kogyo Co., Ltd. was used to measure the volume resistivity value.

[Table] As is clear from Table 1, the layer thickness y of component A is
If it exceeds 47μ, the drawability during spinning will deteriorate, and the mechanical strength and elongation characteristics of the monofilament will also deteriorate. Also, when y is smaller than 2.9μ, the y of the yarn cross-sectional shape
This causes unevenness in the layer thickness, resulting in instability and a decrease in conductive performance. The formula described in the claims,
For those having a layer thickness within the range that satisfies the formula at the same time, in addition to the reeling properties, cross-sectional shape, and physical properties,
It is satisfactory as a bristle material for a hairbrush, and has excellent conductive performance compared to a single yarn containing only component B without conductive component A. Example 2 Using the conductive component A described in Example 1 and polycaproamide with a sulfuric acid relative viscosity of 3.2 as component C,
Using a spinning machine and stretching ratio in the same manner as in Example 1
It was drawn at 4.55 times to obtain a triple core-sheath composite monofilament with a diameter of 0.55 mm. The cross-sectional shape is such that component C is placed in the outermost layer and the center layer, and component A is placed in the middle layer, and the thickness xμ of the outermost layer and the thickness yμ of the middle layer are changed as shown in Table 2, and the conductive component A is A single yarn containing only component C was produced. The obtained monofilament drawn yarn was heated to the same temperature in the bath as in Example 1.
The bristle material was heat-set for straightening at 180°C and used as a bristle material for hair brushes.

[Table] As is clear from Table 2, the thickness of the outermost layer is 60μ
There is a problem in terms of electrical conductivity, and those in which the thickness of the intermediate layer exceeds 50μ not only shows poor drawability during spinning but also has problems in physical properties. In addition, if it is less than 2 μm, there is no problem in spinning properties, but the thickness of the component A layer is unstable, and it is not preferable in terms of electrical conductivity. If the layer thickness is within the range that simultaneously satisfies the above formulas and formulas, there will be no problems in spinning properties, cross-sectional shape, and physical properties as a bristle material for hair brushes.
It has particularly excellent conductivity compared to a single yarn that does not contain a conductive layer.

Claims (1)

[Scope of Claims] 1 Polyamide A containing conductive carbon black and polyamide B which essentially does not contain conductive carbon black, the above A layer having a triple core-sheath structure (when x>0 in the following formula) A concentric core-sheath composite monofilament with a wire diameter D of 400μ or more, which is arranged to form an intermediate layer or a sheath layer of a double core-sheath structure (when x=0 in the following formula), and is essentially made of the above-mentioned polyamide. The thickness of the outermost layer made of B is x (μ), the thickness of the intermediate layer made of polyamide A is y (μ),
When the wire diameter of the monofilament is D (μ),
A bristle material for a hairbrush comprising a composite monofilament having a cross-sectional shape that simultaneously satisfies the following formula and the formula, and having a volume resistivity of 10 ⁸ Ω·cm or less. D−2x−√4 ² −4+0.98 ² ≦2y≦D −2x−√4 ² −4+0.7 ² …… 0≦x≦50 …… 2 Polyamide (A) or (B) is polycaproamide , polyhexamethylene adipamide, and polyhexamethylene sebamide.
Bristle material for hair brushes as described in Section 1. 3. The bristle material for a hairbrush according to claim 1 or 2, wherein the content of conductive carbon black in the polyamide (A) is 5 to 55% by weight.