JP2001192929A - Polyethylene staple fiber and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of simply and efficiently producing, at a low cost, polyethylene staple fibers which are hardly charged with electrostatic electricity, have excellent dispersibility, and are especially suitable for being compounded with rubbers. SOLUTION: This method of producing the polyethylene staple fibers is characterized by melt-spinning polyethylene to form the undrawn fibers, heating and drawing the undrawn fibers, simultaneously imparting a small amount of an oiling agent to the polyethylene fibers formed by the heating and drawing treatments by the use of an oiling agent-imparting means, and then cutting the oiling agent-imparted polyethylene fibers. A mode that the oiling agent- imparting means is a coating roller, a mode that the adhesion amount of the oiling agent is 3 to 35 wt.% based on the total amount, a mode that the oiling agent contains an oil and water in amounts of 1.5 to 33.5 wt.% and 1.5 to 33.5 wt.%, respectively, based on the polyethylene, and so on, are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene staple fiber which is particularly suitable for compounding rubber, and a method for efficiently producing the polyethylene staple fiber.

[0002]

2. Description of the Related Art Conventionally, polyethylene staple fibers have been produced by melt-spinning polyethylene, followed by hot drawing and cutting. In the production of this polyethylene short fiber, an oil agent has been used for the purpose of preventing the polyethylene fiber from scattering or for the purpose of lubrication.
The attached amount of the oil agent on the surface of the polyethylene staple obtained by cutting the polyethylene staple is 1% by weight or less based on the polyethylene staple, and the polyethylene staple is easily charged with static electricity and has poor dispersibility. Was. In particular, when the polyethylene short fibers are blended together and when the polyethylene short fibers are blended with rubber,
The problem that the dispersibility of the polyethylene short fibers was poor was remarkable. For this reason, when blending the polyethylene staples or when using the polyethylene staple as an additive or blending material, static electricity is removed from the polyethylene staple, or another type of oil agent is used. And so on.

[0003] Therefore, in order to increase the amount of an oil agent attached to polyethylene short fibers, for example, polyethylene is melt-spun, hot-stretched, crimped, and the like.
It is also known to produce polyethylene short fibers by attaching the oil agent by immersing it in an oil agent and then cutting the oil agent. However, in this case, since the amount of the oil agent adhering to the polyethylene staple fiber is as large as about 22% by weight, it is necessary to remove the excess oil agent adhering to the polyethylene staple fiber by centrifugal separation. There was a problem that it could not be simply and efficiently manufactured at a low cost.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention provides a method for producing polyethylene staple fibers which are less likely to be charged with static electricity, have excellent dispersibility, and are particularly suitable for rubber compounding, and polyethylene staple fibers which can be produced easily and efficiently at low cost. The aim is to provide a method.

[0005]

Means for Solving the Problems <1> Polyethylene is melt spun to form an undrawn yarn, and while the undrawn yarn is hot drawn, a small amount of an oil agent is applied to the surface of the polyethylene fiber formed by the hot drawing. A method for producing polyethylene staple fiber, characterized in that an oil agent is attached to the polyethylene fiber using an oil agent attaching means to be attached, and then the polyethylene fiber is cut. <2> The above <1>, wherein the oil agent applying means is an application roller.
3. The method for producing polyethylene short fibers described in 1. above. <3> The adhesion amount of the oil agent is 3 to
The method for producing polyethylene short fibers according to <1> or <2>, wherein the amount is 35% by weight. <4> The oil contains oil and water, and the amount of the oil attached is
The production of polyethylene short fibers according to <1> or <2>, wherein the oil content is 1.5 to 33.5% by weight and the water content is 1.5 to 33.5% by weight based on polyethylene fibers. Is the way. <5> The adhesion amount of the oil agent is 5 to polyethylene fiber.
The method for producing polyethylene short fibers according to <1> or <2>, wherein the content is 22% by weight. <6> The method for producing a polyethylene short fiber according to any one of <1> to <5>, wherein a crimping treatment is performed after the oil agent is attached to the undrawn yarn and before cutting. <7> A polyethylene staple produced by the method for producing a polyethylene staple according to any one of <1> to <6>. <8> The polyethylene short fiber according to <7>, which is used for compounding rubber.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a polyethylene short fiber of the present invention and a method for producing the same will be described. In the method for producing polyethylene staple fiber of the present invention, polyethylene is melt-spun to form an undrawn yarn, and while the undrawn yarn is hot drawn, a small amount of an oil agent is added to the surface of the polyethylene fiber formed by the hot drawing. After the oil agent is attached to the polyethylene fiber using the oil agent attaching means to be attached, the polyethylene fiber is cut. The polyethylene short fiber of the present invention is produced by the method for producing a polyethylene short fiber of the present invention.

The polyethylene is not particularly limited and its molecular weight, density and the like can be appropriately selected according to the purpose. For example, low-density polyethylene (LDP)
E), high-density polyethylene (HDPE), etc., and may be any of branched, linear or the like. Any of a mixture with a crystalline polymer may be used.

[0008] Melt spinning of the polyethylene can be carried out by a known spinning method and spinning apparatus. Spinning conditions such as the number of spinnerets, spinneret diameter, spinning temperature, spinning speed, and dry / wet spinning are appropriately determined according to the purpose. You can choose. The spinning speed is usually 2500 m / min or less. If the spinning speed is too low, only an undrawn yarn with a very low orientation may be obtained, and cutting is likely to occur during drawing, and is about 500 m / min. Is preferred.

When melt-spinning the polyethylene,
Known additives appropriately selected as needed may be added to the polyethylene. As the additive,
For example, oxides of metals such as Ti, Si, Al, and Fe are preferably used. When the polyethylene contains the oxide of the metal, in the undrawn yarn discharged from the spinning port, the oxide of the metal serves as a nucleating agent, and crystallization is accelerated, and the orientation of the undrawn yarn is changed. It is advantageous in that it proceeds.

[0010] The decitex of the undrawn yarn formed by melt spinning of the polyethylene varies depending on the purpose and cannot be specified unconditionally.
About 0 dtex is preferable. The undrawn yarn may be wound around a roll or the like before being hot drawn, and may be bundled to form a yarn bundle.

The hot stretching can be performed by a known hot stretching method, a hot stretching apparatus, or the like, and the hot stretching conditions such as the hot stretching temperature and the hot stretching ratio can be appropriately selected according to the purpose. . The heat stretching temperature is usually 4
It is about 0 to 150 ° C. If the stretching temperature is lower than 40 ° C., the stretching tension may be too high, and the stretchability may be reduced. If the thermal drawing ratio is less than the natural drawing ratio (hereinafter referred to as “NDR”) of the undrawn yarn, a large number of undrawn portions will remain, resulting in occurrence of staining spots and many yarn breaks in post-processing. is there.

The thermal stretching can be performed, for example, by winding the yarn bundle between a first roller (heat roller) and a second roller while changing the winding speed of both.

In the present invention, an oil agent is attached to the polyethylene fiber formed by the hot drawing using an oil agent attaching means. The oil agent attaching means is not particularly limited as long as it has a function of attaching a small amount of oil agent to the surface of the polyethylene fiber, and can be appropriately selected depending on the purpose. Here, the “small amount” means that the excess amount of the oil agent does not drop or flow down from the polyethylene fiber when the oil agent is attached to the polyethylene fiber.

As a specific example of the oil agent attaching means, a contact type in which an oil agent is adhered in a small amount while being in contact with the surface of the polyethylene fiber may be used. A separation type in which a small amount of an oil agent adheres to the surface of the polyethylene fiber from a position separated therefrom may be used. As the contact type,
A suitable example is an application roller. As the separated type, a coating spray or the like is preferably exemplified. Note that, for example, a dip coating device cannot apply a “small amount” of the oil agent, and is not suitable in the present invention.

These oil agent attaching means may be used alone or in combination of two or more. Among these, an application roller is particularly preferable in that an oil agent can be continuously and uniformly applied to the polyethylene fiber formed by the hot drawing.

As a preferred specific example of the application roller, a rotary roller arranged so that a part of a peripheral side surface thereof can come into contact with the oil agent is preferably exemplified. In the case of the rotating roller, for example, the rotating roller can be arranged so as to be in contact with the lower side of the polyethylene fiber that moves by being drawn by a roller or the like. In this case, for example, an oil agent is arranged below the rotating roller so that a part of the peripheral side surface of the roller contacts the oil agent. For this reason, the oil agent adheres to the surface of the rotating roller, but excess oil agent on the surface of the rotating roller flows down in the direction of gravity, that is, below the rotating roller. The amount of oil applied is always controlled to a small amount. Since the rotating roller rotates with the movement of the polyethylene fiber that is stretched by heat and wound on a roller or the like, the oil agent is continuously attached to the polyethylene fiber, and the amount of the oil agent is small. And uniform.

If the polyethylene fiber is immersed and dipped in the oil agent without using the oil agent attaching means, a large amount of the oil agent adheres to the polyethylene fiber. It is not preferable in that it is necessary to remove the excess oil agent by performing such treatment (the number of steps must be increased). On the other hand, when the oil agent attaching means is used, this is not the case, and it is preferable in that the amount of the oil agent attached to the polyethylene fiber can be adjusted to be small.

The application of the oil agent by the oil agent applying means must be performed at the latest before the cutting, and when the crimping treatment or the like is performed before the cutting, it is performed before the crimping treatment or the like. Is preferred. The attachment of the oil agent by the oil agent attaching means may be performed during the thermal stretching or may be performed after the thermal stretching. In the former case,
For example, it is possible to arrange the oil agent attaching means between the first roller and the second roller, in the latter case,
For example, the oil applying means can be arranged near the second roller.

The amount of the oil agent attached to the polyethylene fiber is preferably 3 to 35% by weight, more preferably 5 to 22% by weight, and still more preferably 12 to 22% by weight based on the polyethylene fiber. When the adhesion amount of the oil agent is less than 3% by weight, static electricity is easily generated in the polyethylene short fiber, and a pill is easily formed when blended in a composition or the like.
The dispersibility of the polyethylene short fibers may be worse,
If the amount exceeds 35% by weight, the amount of the oil agent is too large.
Workability may be poor.

The oil agent generally contains an oil component and water. The amount of the oil component is preferably 1.5 to 33.5% by weight based on the polyethylene fiber. Is preferably 1.5 to 33.5% by weight.

The oil agent is not particularly limited as long as it is generally used to be applied to a drawn fiber, and examples thereof include those described in JP-A-9-324368. Specifically, oils such as isotridecyl stearate, mineral oil, POE castor oil, POE oleyl ether, POE nonyl phenyl ether, sodium salt of lauryl sulfonate and potassium salt of POE lauryl ether phosphate are dissolved in water such as water. And the like, and the like. These may be included alone or in combination of two or more.

After the oil agent is applied to the polyethylene fiber by the oil applying means, the polyethylene fiber is cut. However, in the present invention, crimping may be performed, if necessary, before the cutting. An appropriately selected process such as a process and a drying process may be performed.

The crimping treatment can be performed using a known crimping device such as a stuffer-type crimping device or a push-in crimper. The number of crimps given to the polyethylene fiber by the crimping treatment is not particularly limited, but it takes into account the tendency of sinking of a single yarn into a cylinder or undesired unwoven fabric, which tends to hinder productivity. Then, about 10 to 20 peaks / 25 mm is preferable.

The cutting of the polyethylene fiber can be performed using a known cutting means such as a cutter. As a result of the cutting, polyethylene short fibers are produced.

The decitex of the polyethylene staple fiber obtained as described above is not particularly limited and can be appropriately selected according to the purpose. When blended with rubber, the decitex is preferably 0.1 to 1000 decitex, ~ 80
0 dtex is more preferred.

Average length (L) of the polyethylene short fiber
Is not particularly limited and may be appropriately selected depending on the purpose. However, 2 to 20 mm is preferable, and 4 to 10 m
m is more preferred. When the average length (L) is less than 2 mm, the performance of the polyethylene short fiber may not be sufficiently exhibited, and when the average length (L) is more than 20 mm, the dispersibility of the polyethylene short fiber at the time of kneading with rubber decreases. Sometimes.

As described above, according to the method for producing polyethylene staple fiber of the present invention, there is no need to remove excess oil or the like.
High-quality polyethylene short fibers can be produced simply and efficiently at low cost.

The polyethylene staple fiber of the present invention produced by the method of producing a polyethylene staple fiber of the present invention is hardly charged with static electricity even when it is packed and transported in a rubber bag or the like. Even when used, the polyethylene short fibers do not become entangled with each other to form a pill, so that the polyethylene short fibers can be suitably used as an additive or the like, have excellent dispersibility, and can be suitably used particularly for rubber compounding. it can.

The rubber is not particularly restricted but includes, for example, a rubber composition for a tire. The rubber composition for a tire contains at least one selected from natural rubber and diene-based synthetic rubber, and further, if necessary, carbon black, process oil,
It contains other appropriately selected components such as stearic acid, zinc white, an antioxidant, a vulcanization accelerator, and sulfur. The diene-based synthetic rubber is not particularly limited and can be appropriately selected from known rubbers according to the purpose. Examples thereof include a styrene-butadiene copolymer, a styrene-isoprene copolymer, and polyisoprene. And polybutadiene.

[0030]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Examples 1 to 10 and Comparative Examples 1 and 2 High-density polyethylene chips (HDPE, weight average molecular weight (M
w) = 1.8 × 10 ⁵ , melting point peak temperature (melting point) = 135 ° C. measured with a DuPont DSC at a rate of temperature increase of 10 ° C./min and a sample weight of 5 mg) by melt spinning using a spinning apparatus. To form an undrawn yarn. The undrawn yarn was hot drawn to form a polyethylene fiber, and an oil agent was applied to the surface of the polyethylene fiber using an application roller. In addition, the said application roller was arrange | positioned so that it could contact the lower side of the polyethylene fiber formed by heat drawing, and was rotatable. An oil agent is arranged below the application roller,
Part of the peripheral side surface of the application roller was brought into contact with the oil agent. The adhesion amount of the oil agent is as shown in Table 1. Further, the breakdown of the oil content and the water content in the amount of the oil agent attached is as shown in Table 1.

The oil agent is disclosed in JP-A-9-32
No. 4368, isotridecyl stearate 35% by weight, mineral oil 35% by weight, POE castor oil 1
2% by weight, POE oleyl ether 10% by weight, POE
A mixed oil obtained by dissolving an oil containing 3% by weight of nonylphenyl ether, 3% by weight of sodium lauryl sulfonate and 2% by weight of potassium salt of POE lauryl ether phosphate in water was used.

The polyethylene staple fiber thus obtained is
It was added to and mixed with the following rubber composition, and the dispersibility of the polyethylene short fibers at that time was evaluated as follows. That is,
The following rubber composition was formed into a sheet having a thickness of 0.8 mm, and the polyethylene staple was wrapped with the sheet and passed through a 3 inch roll having a width of 3 mm five times to obtain a sheet having a width of 0.8 m.
m was passed twice through a roll having a width of 3 mm, and once passed through a roll having a width of 3 mm.
This evaluation sample was cut, and the size (diameter) and the number of pills (pills) present in a portion within 3 cm from the bottom surface in the cross section were measured at 10 points. The results are shown in Table 1. In addition, the number of "pills" in Table 1 shows the total when measuring 10 places.

The rubber composition is based on a rubber component containing 70% by weight of natural rubber and 30% by weight of butadiene rubber, 50% by weight of carbon black, 2.0% by weight of process oil, 1.5% by weight of stearic acid. %, Zinc white 3.
0% by weight, antioxidant 1.0% by weight, vulcanization accelerator 0.7
% By weight and 1.2% by weight of sulfur.

[0035]

[Table 1]

(Examples 11 to 16 and Comparative Examples 3 and 4) An oil agent was adhered to the polyethylene short fibers obtained in the same manner as in Example 1 in the same manner as in Example 1 to obtain polyethylene short fibers. However, the adhesion amount of the oil agent was as shown in Table 2. With respect to the obtained polyethylene short fibers, static electricity was measured as described below. The results are shown in Table 2. That is, 150 g of polyethylene short fiber was placed in a rubber bag, and the rubber bag was shaken up and down 10 times, and the surface potential was measured. The surface potential was measured using a digital electrostatic potentiometer (KSD-0102, manufactured by Kasuga Electric Co., Ltd.).
And the surface potential was not per single polyethylene short fiber, but per bulk. The lower the surface potential, the less static electricity, that is, the better the dispersibility.

The rubber bag is made of cis-1,4-polybutadiene (BR0, manufactured by JSR Corporation).
1), carbon black (Asahi Carbon Co., Ltd., Asahi # 8)
0: carbon N220), an anti-aging agent (Nocrack 6C, manufactured by Ouchi Shinko Chemical Co., Ltd.), dibenzothiazyl sulfide, and a rubber composition containing N-cyclohexyl-2-benzothiazyl-sulfenamide in a bag shape. It is molded into.

[0038]

[Table 2]

[0039]

According to the present invention, the above-mentioned conventional problems can be solved, and it is difficult to generate static electricity, the dispersibility is excellent, and the polyethylene short fiber which is particularly suitable for rubber compounding. It is possible to provide a method for producing polyethylene short fibers that can be produced simply and efficiently at low cost.

Claims (8)

[Claims] 1. An oil agent attaching means for melt spinning polyethylene to form an undrawn yarn, and applying a small amount of an oil agent to the surface of the polyethylene fiber formed by the hot drawing while thermally drawing the undrawn yarn. A method for producing polyethylene staple fibers, comprising: attaching an oil agent to the polyethylene fibers and cutting the polyethylene fiber. 2. The method for producing polyethylene short fiber according to claim 1, wherein the oil agent attaching means is an application roller. 3. The method for producing polyethylene short fibers according to claim 1, wherein the amount of the oil agent attached is 3 to 35% by weight based on the polyethylene fibers. 4. The oil agent contains oil and water, and the amount of the oil agent is 1.5 to 3 with respect to the polyethylene fiber.
3.5% by weight, and the water content is 1.5 to 33.5% by weight.
The method for producing polyethylene short fiber according to claim 1 or 2, wherein 5. The method for producing polyethylene short fibers according to claim 1, wherein the amount of the oil agent attached is 5 to 22% by weight based on the polyethylene fibers. 6. The method for producing polyethylene short fibers according to claim 1, wherein a crimping treatment is performed after the oil agent is attached to the undrawn yarn and before cutting. 7. A polyethylene short fiber produced by the method for producing a polyethylene short fiber according to any one of claims 1 to 6. 8. The polyethylene short fiber according to claim 7, which is used for rubber compounding.