JPH0116923B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a flame-retardant polyethylene filament, and more particularly to a flame-retardant polyethylene filament that has excellent flame retardancy and mechanical properties, good productivity, and little unevenness in yarn quality. [Prior Art] Polyethylene filaments are widely used in many industrial fields because of their excellent moldability, chemical properties, mechanical properties, and electrical properties, as well as their low cost. However, polyethylene filaments are easily flammable, and once ignited, they have the serious drawback of violently igniting and spreading, and cannot be used for some purposes. For example, interior products such as curtains and carpets, and industrial materials products such as construction sheets and fiberboard, are already subject to flame-retardant laws and regulations depending on the location where they are used, and they are also made to prevent paint from scattering. In recent years, there has been an increasing demand for flame retardancy for textile products such as nets and sheets for industrial use, shipbuilding, windproofing, insect proofing, and sand control. Of course, this is not possible with ordinary polyethylene filament,
There is a strong desire to make it flame retardant. Various methods have been known to make polyethylene resin flame retardant, but the most typical method is to add a flame retardant consisting of a halogen-containing compound and antimony oxide to polyethylene resin. Therefore, attempts have been made to apply this method to the production of flame-retardant polyethylene filaments. [Problems to be Solved by the Invention] However, since the viscosity of polyethylene resin does not decrease so greatly when it is heated and melted, it is more difficult to form filaments by melt spinning than to manufacture general polyethylene molded products by injection molding or extrusion molding. It is necessary to heat the resin to a much higher temperature of 240-280℃, but under such high temperature conditions, the halogen-containing compounds mentioned above tend to thermally decompose, resulting in coloration and rough skin of the filament. Troubles such as filaments or decomposition products accumulating in the nozzle tube and causing yarn unevenness or yarn breakage tend to occur frequently, making it extremely difficult to manufacture filaments of good and stable quality with high productivity. Have difficulty. On the other hand, if the amount of flame retardant added is reduced to avoid these drawbacks, there is a problem that the flame retardant performance of the filament is insufficient.
At present, a flame-retardant polyethylene filament that satisfies both quality and productivity has not yet been found. The present invention was made in view of the problems of the prior art as described above, and its purpose is to maintain high flame retardant performance and excellent physical properties inherent to polyethylene resin, and to maintain stable quality. An object of the present invention is to provide a flame-retardant polyethylene filament that has a high flame retardancy. Another object of the present invention is to provide a flame-retardant polyethylene filament that can be produced with high efficiency and has almost no occurrence of yarn breakage or stretching breakage during spinning. [Means for solving the problem] The above purpose is to add (a) 3 to 10 parts by weight of an organic bromine compound (b) 0.2 to 0.5 times the amount of organic bromine compound (a) to 100 parts by weight of polyethylene resin. amount of antimony trioxide (c) 0.02 to 0.15 times the amount of metal soap (d) of the organic bromine compound (a) and antimony trioxide (b) A flame-retardant polyethylene filament obtained by melt-spinning a composition containing white carbon in an amount of 0.05 to 0.2 times the total amount and (e) an antioxidant in an amount of at least 0.01 times the amount of organic bromine compound (a). It will be done. In the flame-retardant polyethylene filament of the present invention having the above-mentioned structure, the organic bromine compound and antimony trioxide act as flame retardants, and this gives the polyethylene filament a high degree of retardancy. Metal soap, white carbon, and antioxidants, especially the first two, have a synergistic effect on this property.
In the presence of the flame retardant in the amount necessary to impart the above-mentioned high flame retardance, and despite the harsh conditions of high-temperature melt spinning, yarn breakage occurred during the spinning and drawing processes, and the denier The purpose is to suppress the occurrence of unevenness, etc., and to make it possible to stably produce high-quality flame-retardant polyethylene filaments with good productivity. The reasons why such effects can be achieved by these compounding agents are not all clear, but metal soaps and white carbon are thermal decomposition products present in the spinning composition or It prevents pigments from agglomerating and depositing on the inner wall of the cylinder or die of the extruder, or the grooves of the screw, thereby preventing yarn breakage during the drawing process due to the agglomerates being mixed into the filament. In addition to preventing generation and deterioration of yarn quality, it also suppresses the formation of deposits consisting of thermal decomposition products etc. around the exit of the nozzle when the composition is extruded from the pores of the nozzle, thereby reducing the risk of damage during the spinning process. The antioxidant contributes to solving problems such as thread breakage and uneven denier, and also improves the mechanical strength of the filament by preventing thermal decomposition (dehydrohalogenation reaction) of organic bromine compounds. It is inferred that this synergistic effect prevents deterioration of color tone and deterioration of color tone, and thus enables stable continuous spinning over a long period of time and the acquisition of high-quality polyethylene filaments. Even if any of these compounds is absent, the effects of the present invention cannot be achieved (see Examples below). In the present invention, high-density polyethylene is generally used as the polyethylene resin, but there is no problem in using a small amount (up to about 30% by weight) of low-density polyethylene in combination. Furthermore, if necessary, it is also possible to use a material into which other polyolefin components are introduced in an amount of up to about 30% by weight by copolymerization or blending. However, in any case, the melt flow rate (MFR) of the polyethylene resin used is
It is preferably within the range of 0.2 to 3.0, particularly 0.6 to 1.2. If the MFR is less than 0.3, the extrusion properties during melt spinning will be poor, the dispersibility and compatibility of the compounding agents will also be very poor, and the stretchability in the subsequent drawing step will tend to be low. On the other hand, when the MFR becomes too large, exceeding 3.0, the strength tends to decrease. The organic bromine compound acts as a main flame retardant to impart flame retardancy to the above-mentioned polyethylene resin, and from the viewpoint of such flame retardant effect, the bromine content is preferably 50% by weight or more. . Further, it is particularly desirable that the melting point (or decomposition point) is 250°C or higher. If the bromine content is less than 50% by weight, the amount required to impart the desired flame retardancy to the polyethylene filament increases, resulting in a decrease in yarn quality and poor operability due to the occurrence of yarn breakage. This will lead to a decrease in In addition, those with a melting point or decomposition temperature of less than 250°C are severely decomposed and deteriorated by the heat during melt spinning, resulting in a significant disadvantage in flame retardant performance and operability. Preferred specific examples of organic bromine compounds include bisphenol compounds such as tetrabromobisphenol A and tetrabromobisphenol S.
and derivatives thereof, and diphenyl compounds such as polybrominated diphenyl oxide, polybrominated diphenyl sulfone, and derivatives thereof. The blending ratio of this organic bromine compound is 3 to 10 parts by weight, preferably 5 to 7 parts by weight, per 100 parts by weight of the polyethylene resin; if it is less than 3 parts by weight, a sufficient flame retardant effect cannot be obtained; If the amount is more than 10 parts by weight, it not only makes stable operation difficult, but also causes a decrease in the mechanical strength of the filament and an increase in cost, which is undesirable. The antimony trioxide used in combination with the above organic bromine compound should have an average particle size of 5 μm or less, preferably around 1.5 μm, a purity of 99.7% or more, and a moisture content of 99.7% or more.
A content of 0.2% or less is preferably used. This antimony trioxide imparts excellent flame retardancy to polyethylene filaments due to its synergistic effect with organic bromine compounds. Therefore, its amount is closely related to the amount of organic bromine compound, and the latter
It is important that the amount is in the range of 0.2 to 0.5 times, preferably in the range of 0.3 to 0.4 times. If the amount is less than 0.2 times the amount, the effect of improving flame retardancy will be low, and if the amount is more than 0.5 times the amount, problems such as a decrease in fiber strength and extremely reduced operability will occur, which is not preferable. As the metal soap, fatty acid metal salts such as lithium stearate, lead stearate, barium stearate, calcium stearate, magnesium stearate, lithium oleate, barium laurate, zinc laurate, or barium benzoate can be used. However, the use of lithium stearate is particularly effective. Further, two or more of these metal soaps may be used in combination. The amount of metal soap to be blended is such that it satisfies 0.02 to 0.15 times the total amount of the organic bromine compound and antimony trioxide. If the blending amount is less than 0.02 times the total amount of the organic bromine compound and antimony trioxide, the blending effect will not be sufficient, and yarn breakage will occur during the spinning and drawing processes, reducing operability. The dispersion state of antimony trioxide and the like becomes poor, resulting in adverse effects such as uneven denier and uneven thread quality. On the other hand, if the amount exceeds 0.15 times, the composition will absorb moisture, causing problems such as yarn breakage during spinning due to causes such as foaming. The white carbon referred to in the present invention is powder of silicic acid compounds such as anhydrous silicic acid, hydrated silicic acid, aluminum silicate, calcium silicate, and magnesium silicate. The best results are obtained when The amount of white carbon blended is in the range of 0.05 to 0.2 times, preferably 0.07 to 0.15 times the total amount of the organic bromine compound and antimony trioxide. If the blending amount is less than 0.05 times the amount, a sufficient blending effect cannot be obtained, while if the blending amount exceeds 0.2 times the amount, spinning operability or mechanical strength of the filament will decrease, both of which are unsuitable. Examples of antioxidants include phosphorus antioxidants such as triphenyl phosphite, diphenylnonylphenyl phosphite, diphenylisodecyl phosphite, and trisnonylphenyl phosphite, butylated hydroxyanisole (BHA), and stearyl- Monophenolic antioxidants such as β-propionate are preferably used. Among these antioxidants, stearyl-β-
Propionate is particularly good. When blending, the antioxidant is used in an amount equivalent to at least 0.01 times the blended amount of the organic bromine compound. If the amount is less than 0.01 times, a sufficient blending effect will not be obtained and spinning productivity will decrease. On the other hand, there is no particular restriction on the upper limit of the amount of the organic bromine compound, but even if more than 0.05 times the amount of the organic bromine compound is added, no further improvement in the combination effect can be expected and the cost will only increase unnecessarily. It is better to keep it below this level. In addition, among the above compounds, in the case of substances that do not melt at the melt spinning temperature of polyethylene resin (usually 240 to 280 ° C.), such as organic bromine compounds having a melting point higher than the temperature, or white carbon, etc.,
From the viewpoint of maintaining the mechanical properties of the polyethylene filament, it is desirable to use particles whose average particle diameter is about 30 μm or less. The spinning composition of the present invention having the above composition may further contain pigments, ultraviolet absorbers,
UV stabilizers etc. can be added. The process of melt-spinning this spinning composition to produce the flame-retardant polyethylene filament of the present invention can be carried out according to a conventional method. That is, the polyethylene resin and each compound are measured and mixed in the amounts as described above, and then kneaded in advance using a mixing roll, Banbury mixer, etc., or directly fed to an extruder such as a screw extruder. This is sufficiently melted in the cylinder section, extruded, and discharged from the die/nozzle section. In this case, foreign substances such as coarse particles of the compound or air bubbles are present in the spinning melt, and if they are mixed into the undrawn yarn, it can cause problems such as yarn breakage in the drawing process. , it will cause a decrease in operability and a decrease in yield.
It is important to avoid contamination with foreign matter as much as possible. In this case, the amount of coarse particles to be blended can be dealt with by prior pulverization or by passing through a screen. on the other hand,
To prevent the inclusion of air bubbles, it is necessary to thoroughly dry the raw materials and to adjust the temperature of the final zone of the cylinder section of the extruder to the temperature of the die, as is commonly done when spinning polyethylene filaments containing hygroscopic additives such as carbon black. It is particularly effective to maintain the temperature about 30 to 60°C lower. The temperature of the die should preferably be as low as possible from the perspective of preventing thermal decomposition of the organic bromine compound in the spinning composition, but if it is too low, the flow of the polyethylene resin will be poor, the surface will be rough, and thread breakage will occur. Therefore, it is generally preferable to maintain the temperature in the range of 240 to 280°C, and most preferably in the range of 250 to 260°C, taking into consideration the stability of the organic bromine compound. The temperature of the extruder cylinder section is
Considering the above die temperature conditions, it is generally 200 to 250℃.
will be adopted. The undrawn yarn discharged from the extruder die/nozzle in this manner is then cooled in a cooling tank and then drawn in a drawing tank. The temperature of the cooling bath at this time is maintained at 20 to 50°C, which is the same as in the production of ordinary polyethylene filament. Further, the temperature of the stretching tank may be kept under normal conditions and is generally maintained at 96 to 99°C. The stretching ratio may be in the range of 5 to 15 times, which is generally employed in the production of polyethylene filaments, and an appropriate one is selected from this range depending on the use of the filament. After the above cooling and stretching are completed, the filament is then subjected to heat treatment using hot water or moist heat as required, and then wound up in accordance with a conventional method to obtain the flame-retardant polyethylene filament of the present invention. Regarding the fineness of the filament, in the case of the present invention
It is generally and preferable to have a denier of 150 to 3000, but in some cases it is possible to use a finer or thicker denier. The present invention will be explained in more detail below using Examples. It should be noted that all figures in the middle part of the examples and % are related to weight [excluding elongation (%)]. In addition, filament strength and elongation, flame retardancy (limit oxygen index,
The number of times of flame contact) and spinning operability were measured by the following test methods. [Strong elongation] Shorter type tensile testing machine (manufactured by Asano Kikai Seisakusho)
using a gripping interval of 500mm and a pulling speed of 500mm/
Measured under the following conditions: min, temperature 20°C, humidity 65% RH. [Flame retardancy] (1) Limiting oxygen index The sample yarn was pressed at 200°C into a flat plate with a thickness of 3 mm. A test piece with a width of 6.5 mm and a length of 120 mm was cut from this flat plate and tested using an oxygen index type flammability tester (ON-1 type manufactured by Suga Test Instruments) under JIS standards.
The critical oxygen index was determined using the flammability test method for polymer materials using the oxygen index method of K7201. (2) Number of times of flame contact Twist the sample yarn to 10 cm long and 1 g using a flame resistance test device (SFT manufactured by Daiei Kagaku Seiki Seisakusho)
The number of times of flame contact was measured using the 45° coil method of the Ministry of Home Affairs Fire and Disaster Prevention Test Regulations (Ministry of Home Affairs Ordinance No. 3). [Spinning operability] Continuous operation was performed for 48 hours, and the operability was ranked as follows based on the occurrence of yarn breakage during that time. Operability rank Thread breakage occurrence status A: No thread breakage occurred at all. B: Thread breakage occurred 1 to 3 times. C: Thread breakage occurred 4 to 8 times. D: Thread breakage occurred 9 or more times. Example 1 High density polyethylene [MFR0.8g/10min (230
℃, load 2.16Kg/cm ² )], polybrominated diphenyl oxide [Nonene DP-10] was added as an organic bromine compound.
(F), manufactured by Marubishi Yuka Kogyo Co., Ltd.: average particle size 10 μm, 200
Mesh sieve residue 0.01%, melting point 310℃, bromine content
84%], antimony trioxide (average particle size 1 μm, antimony trioxide component 99.7%, moisture content 0.1%), lithium stearate as metal soap, silicic anhydride as white carbon, stearyl-β-propionate as stabilizer. The mixture was put into a mixing roll at the mixing ratio shown in Table 1, heated and kneaded at 170 to 180°C for 15 minutes, and formed into pellets using a pelletizer equipped with a vented extruder. This was put into an extruder with a screw diameter of 60 mmφ and a monofilament die with 80 small holes with a nozzle diameter of 1.2 mmφ attached to the tip, and the temperature of the extruder was set to 220℃ at the cylinder tip and 255℃ at the die/nozzle section. The undrawn yarn was extruded by adjusting the The extruded undrawn yarn was passed through a cooling tank adjusted to a temperature of 35°C to be rapidly cooled, and then stretched 10 times in a drawing tank adjusted to a temperature of 99 to 100°C at a spinning speed of 140 m/min. A polyethylene filament with a fineness of 400 denier was obtained. The strength and elongation, flame retardance, and spinning operability of the polyethylene filament thus obtained were investigated, and the results are shown in Table 1.

[Table] As is clear from the results in Table 1, the flame-retardant polyethylene filament of the present invention (Invention Example 1)
Not only is it excellent in flame retardancy, but its mechanical properties are also maintained at desirable values that are sufficiently satisfactory for practical use, and its production operability is extremely good. On the other hand, the conventional flame-retardant polyethylene filament (Comparative Example 2) containing an organic bromine compound and antimony trioxide has good flame retardancy, but its production operability is extremely poor and continuous operation is difficult in practice. It was hot. In addition, variations in mechanical properties and flame retardant performance were also observed in terms of yarn quality. Further, from the results shown in Table 1, it is clear that even if any of the metal soap, white carbon, and antioxidant are absent, the operability will be extremely poor and the object of the present invention cannot be achieved. Example 2 Tetrabromobisphenol S [trade name TBS, manufactured by Matsunaga Chemical Industry Co., Ltd.; average particle size 15μ] was used instead of polybrominated diphenyl oxide as an organic bromine compound.
200 mesh sieve residue 0.02%, melting point 290°C, bromine content 56%], and the proportions of each compound were as shown in Table 2. Example 1 (Invention Example 1)
Polyethylene filaments were obtained in exactly the same manner as described above. Table 2 shows the results of examining strength, elongation, flame retardancy, and spinning operability.

[Table] From the results in Table 2, when the amount of organic bromine compound added to 100 parts by weight of polyethylene resin is less than 3 parts by weight, the flame retardant performance decreases significantly (Comparative Example 6).
On the other hand, it is clear that if the amount exceeds 10 parts by weight, the spinning operability becomes poor (Comparative Example 7). Example 3 Polyethylene filaments were obtained in the same manner as in Example 2 (Invention Example 3) except that the amount of antimony trioxide was varied as shown in Table 3. Table 3 shows the results of examining the strength and elongation, flame retardancy, and spinning operability of these materials. In addition, the third
The results of Inventive Example 3 of Example 2 are listed again in the table.

[Table] As is clear from Table 3, when the amount of antimony trioxide blended was 0.2 to 0.5 times that of the organic bromine compound, excellent mechanical properties, flame retardance, and operability were obtained. A polyethylene filament is obtained. Example 4 Polyethylene filaments were obtained in the same manner as in Example 2, except that the proportions of each compound were changed as shown in Table 4. The strength and elongation, flame retardance, and spinning operability of these filaments were investigated, and the results are shown in Table 4.

[Table] From the results in Table 4, when the amount of metal soap (lithium stearate) is 0.02 to 0.15 times the total amount of organic bromine compound (tetrabromobisphenol S) and antimony trioxide, It is clear that a polyethylene filament with excellent mechanical properties, flame retardance and spinning operability can be obtained. Example 5 Polyethylene filaments were obtained in the same manner as in Example 2 (Invention Example 3) except that the amount of silicic anhydride (white carbon) was changed as shown in Table 5. Table 5 shows the results of examining the strength, elongation, flame retardancy, and spinning operability of these filaments. In addition, Table 5 shows Example 2.
The results of Invention Example 3 are listed again.

【table】

[Table] From the results in Table 5, when the amount of white carbon (silicic anhydride) is 0.05 to 0.2 times the total amount of organic bromine compound (tetrabromobisphenol S) and antimony trioxide, It can be seen that a polyethylene filament with excellent mechanical properties, flame retardance, and spinning operability as desired can be obtained, and spinning operability becomes poor in any case outside these ranges. Example 6 Polyethylene filaments were obtained in the same manner as in Example 2 (Inventive Example 3) except that the amount of stearyl-β-propionate (antioxidant) was varied as shown in Table 6. Regarding the filament obtained here, the strength and elongation, flame retardance, and spinning operability were investigated.
Shown in the table.

[Table] Example 7 The amount of polybrominated diphenyl oxide was varied as shown in Table 7, or the organic bromine compound was replaced with a polybrominated diphenyl sulfone derivative [trade name Nonnene PR-2, Marubishi Co., Ltd.] Manufactured by Yuka Kogyo Co., Ltd.; average particle size 25 μm, 200 mesh sieve residue 0.01%, decomposition point
320℃, bromine content 67%] or tetrabromobisphenol A [trade name Fire master BP4A, manufactured by Michigan Corporation; average particle size 20 μm, 200 mesh sieve residue 0.01%, decomposition point 280
Polyethylene filaments were obtained in the same manner as in Example 1 of the present invention except that the temperature and bromine content were 60%]. The filament thus obtained was examined for strength and elongation, flame retardancy, and spinning operability.
Shown in the table. In Table 7, the results of Inventive Example 1 of Example 1 are listed again.

[Table] Example 8 In the formulation of Inventive Example 1 in Example 1 Metal soap was changed from lithium stearate to lead stearate (Inventive Example 18) or zinc laurate (Inventive Example 19), and white carbon was changed to anhydrous. In addition to changing silicic acid to aluminum silicate (present invention example 20) or magnesium silicate (present invention example 21), and changing the antioxidant from stear-β-propionate to triphenyl phosphite (present invention example 22). Spinning was carried out in the same manner as in Inventive Example 1 of Example 1 to obtain a polyethylene filament. Table 8 shows the results of examining the strength, elongation, flame retardancy, and spinning operability of these filaments.

【table】

〔Effect of the invention〕

The polyethylene filament of the present invention obtained by melt-spinning a composition having the above-mentioned specific composition,
It has high flame retardant performance and maintains the excellent mechanical properties inherent to polyethylene resin, making it useful for various interior products, industrial material products, etc. that require flame retardancy. Furthermore, the flame-retardant polyethylene filament of the present invention has excellent production operability with few occurrences of troubles such as yarn breakage during the spinning process or the drawing process, and has extremely little unevenness in yarn quality.

Claims (1)

[Claims] 1. For 100 parts by weight of polyethylene resin: (a) 3 to 10 parts by weight of an organic bromine compound (b) Antimony trioxide in an amount of 0.2 to 0.5 times the amount of the organic bromine compound (a) (c) Organic Metal soap (d) in an amount of 0.02 to 0.15 times the total amount of the bromine compound (a) and antimony trioxide (b); 0.05 to 0.2 times the amount of the total amount of the organic bromine compound (a) and antimony trioxide (b) A flame-retardant polyethylene filament obtained by melt-spinning a composition containing white carbon and (e) an antioxidant in an amount of at least 0.01 times the amount of an organic bromine compound (a). 2. The flame-retardant polyethylene filament according to claim 1, wherein the polyethylene resin has a melt flow rate (MFR) of 0.2 to 3.0. 3. The flame-retardant polyethylene filament according to claim 2, wherein the polyethylene resin has a melt flow rate (MFR) of 0.6 to 1.2. 4 Polyethylene resin is high-density polyethylene alone, or high-density polyethylene and 30%
A flame-retardant polyethylene filament according to any one of claims 1 to 3, which is a blend with up to % by weight of low-density polyethylene. 5. The flame-retardant polyethylene filament according to claim 1, wherein the organic bromine compound has a bromine content of 50% or more and a melting point or decomposition point of 250°C or more. 6. The flame-retardant polyethylene filament according to claim 5, wherein the organic bromine compound is a bisphenol-based or diphenyl-based bromine compound. 7. The flame-retardant polyethylene filament according to claim 1, wherein the antimony trioxide has an average particle size of 5 μm or less. 8. The flame-retardant polyethylene filament according to claim 7, wherein the antimony trioxide has an average particle diameter of about 1.5 μm. 9. The flame-retardant polyethylene filament according to claim 1, in which lithium stearate is used as the metal soap. 10. The flame-retardant polyethylene filament according to claim 1, in which silicic anhydride is used as the white carbon. 11. The flame-retardant polyethylene filament according to claim 1, wherein the amount of the organic bromine compound blended is 5 to 7 parts by weight based on 100 parts by weight of the polyethylene resin. 12. The flame-retardant polyethylene filament according to claim 1, wherein the amount of antimony trioxide is 0.3 to 0.4 times the amount of the organic bromine compound. 13. The flame-retardant polyethylene filament according to claim 1, wherein the amount of the metal soap is 0.03 to 0.1 times the total amount of the organic bromine compound and antimony trioxide. 14 The amount of white carbon added is 0.07 to the total amount of organic bromine compounds and antimony trioxide.
The flame-retardant polyethylene filament according to claim 1, which is 0.15 times the amount. 15. The flame-retardant polyethylene filament according to claim 1, wherein the amount of the antioxidant is 0.02 to 0.05 times the amount of the organic bromine compound.