JP2711157B2 - Flame retardant composite fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a composite fiber made of a polyolefin-based polymer having excellent flame retardancy and capable of reducing denier.

(Prior art and problems to be solved) Composite fibers formed from a polyolefin-based polymer are:
In general, it is a low-melting point resin that has both the excellent thermal adhesiveness of a low-melting point resin and the stiffness of a high-melting point resin, chemical stability, light weight, and low cost. It is used in many fields such as diapers and other materials for daily life, masks and other filter materials, civil engineering, construction materials, agricultural and horticultural materials.

In recent years, however, there has been a high demand for flame retardancy for related materials with the prevention of flames and various regulations in each of the fields described above. In addition, in applications in which the product is in direct contact with the human body, it is desired that the flame retardant does not exist on the surface of the molded product. Accordingly, various flame-retardant conjugate fibers and methods for producing the same have been proposed for polyolefin-based conjugate fibers, but none of them can sufficiently satisfy individual conditions.

For example, Japanese Patent Publication Nos. 60-2405 and 61-44967 disclose a flame retardant in which a composite fiber comprising two kinds of polyolefin polymers having different melting points contains a flame retardant only in a low melting point component such as polyethylene. Conjugate fiber is disclosed,
In order to maintain good flame retardancy, the selection range of the use ratio of polyethylene and polypropylene as a high melting point component is small and the restriction is large. Further, a flame retardant is added to the polyethylene on the fiber surface, which is not preferable. Tokiko Sho60
No. 7772 discloses a flame-retardant conjugate fiber having a higher flame-retardant effect by separately containing two types of flame retardants having different decomposition temperatures in the high and low melting point components. Since the flame retardant with a high decomposition temperature used does not melt at the fiber molding temperature, fine denier fibers cannot be obtained, and aromatic bromine compounds such as decabrom diphenyl oxide are compared with aliphatic bromine compounds. Since the flame-retardant effect on polypropylene is not sufficient, a large amount of addition is required, which not only increases the price, but also causes yarn breakage,
This causes problems in productivity and quality due to a decrease in thermal adhesion and rough skin. Also in this case, the flame retardant is added to the polyethylene on the fiber surface as described above, which is not preferable.
Japanese Patent Application Laid-Open No. 58-15609 discloses a method for reducing the temperature by incorporating a flame retardant having a decomposition temperature of 100 ° C. or more higher than the melting point of each component of a conjugate fiber and a particle size of 62 μm or less. A fine denier conjugate fiber which is excellent in flame retardancy and thermal adhesiveness in which a relatively large amount of a flame retardant is also blended in the melting point component and which can be produced with good spinnability is disclosed. There is also a point that it is not easy to finely pulverize the fuel,
Under general spinning conditions, a fine denier conjugate fiber may not be formed stably. Also, in this case, a flame retardant is added to the polyethylene on the fiber surface as described above,
Not preferred.

Accordingly, an object of the present invention is to provide a conjugate fiber which has high flame retardancy and excellent weldability at low temperatures without containing a flame retardant on the surface of the fiber, and can stably spin fine denier fibers. Is to do.

(Means for Solving the Problems) The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems of the flame-retardant conjugate fiber, and have found that a composition in which a flame retardant specified only in a propylene polymer having a high melting point is blended is used. By using an ethylene-based polymer, the knowledge of achieving the intended purpose was obtained, and the present invention was completed. That is, according to the present invention, the following (a) composition of a propylene polymer containing a flame retardant is used as a core, and an ethylene polymer (b) containing no flame retardant is used as a sheath. /
The ratio (weight ratio) of (b) is 50/50 to 90/10, and (a) +
Flame-retardant conjugate fiber, characterized in that the amount of etherified bisphenol bisphenol A contained is 0.9 to 9.0 parts by weight based on the total (100 parts by weight) of (b).

(A) per 100 parts by weight of a polymer mainly composed of propylene, with respect to etherified tetrabrominated bisphenol A represented by the following general formula: (Wherein R ₁ and R ₂ in the formula are each an alkyl group bonding at least two bromine atoms of the same or different types) of 0.6 to 10 parts by weight, antimony trioxide of 0.5 to 4.0 parts by weight and higher fatty acid Metal salts (however, elements II and I of the periodic table)
A composition comprising 3 to 30% by weight, based on etherified bisphenol A of tetrabrominated bisphenol A, is provided.

In the composite fiber of the present invention, the propylene-based polymer (hereinafter referred to as a propylene-based polymer) used in the composition (a) constituting the inner core includes propylene homopolymer, ethylene, butene, and the like. Random copolymers, block copolymers of α-olefins and propylene, or mixtures thereof.

Further, as etherified tetrabrominated bisphenol A,
It is represented by the following general formula, Wherein R ₁ and R ₂ are the same or different
It is not particularly limited as long as it is an alkyl group binding at least two bromine atoms, and has 2 to 20, preferably 2 to 5 carbon atoms.
The more the number of bromine atoms bonded to it is two or more, the better the flame retardant effect. Specifically, for example, bisphenol A bis (dibromoethyl ether) tetrabromide, bisphenol A bis (dibromopropyl ether), bisphenol A bis (dibromobutyl ether) tetrabromide,
Bisphenol A bis (tribromopropyl ether) tetrabromide, bisphenol A bis (tetrabromopropyl ether) tetrabromide, bisphenol A bis (tribromobutyl ether), bisphenol A bis (tribromobutyl ether) tetrabromide, etc. Of bisphenol A bis (polybromoalkyl ether) is preferably used. The amount of the etherified tetrabrominated bisphenol A is 0.6 to 100 parts by weight of the propylene polymer.
10.0 parts by weight, preferably 0.7 to 7.0 parts by weight, if the compounding amount is less than the above lower limit, sufficient flame retardant effect can not be exhibited, and if it is more than the above upper limit, the thermal stability becomes poor. The spinning properties such as coloring, thread breakage, etc. are deteriorated.

As antimony trioxide, commercially available products can be used as they are. The amount of antimony trioxide is generally 0.5 to 4.0 parts by weight based on 100 parts by weight of the propylene-based polymer, and if the amount is less than the above lower limit, a sufficient flame retardant effect cannot be exhibited, and When the amount is more than the above upper limit, even if it is blended in a large amount, no improvement in the flame retardant effect is observed, and stable spinnability cannot be obtained.

Examples of salts of higher fatty acids with metals belonging to any of Groups II, III and IV of the periodic table include fatty acids such as stearic acid, lauric acid, myristic acid, behenic acid, palmitic acid and capric acid. Metal salts such as calcium, cadmium, barium, lead, zinc, and aluminum are appropriately used. The blending amount of such a higher fatty acid metal salt is appropriately determined depending on the amount of etherified bisphenol A bisphenol A, and generally 3 to 30% by weight based on the amount of etherified bisphenol A bisphenol A, If the amount is less than the above lower limit, the effect of suppressing the thermal decomposition of the etherified tetrabrominated bisphenol A is not sufficient, and if the amount is more than the above upper limit, the flame retardancy is undesirably reduced.

In the conjugate fiber of the present invention, the (b) ethylene-based polymer constituting the outer sheath (hereinafter referred to as an ethylene polymer) may be a homopolymer of ethylene or an α-olefin such as propylene or butene. Copolymers, such as copolymers with vinyl acetate, generally having a content of 35% by weight or less.

In addition, in the case of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 35% by weight or more, the tackiness is strong when used alone, and the surface state is not preferable. Is not preferable because uniform blending with other ethylene-based polymers cannot be achieved.

Further, the ratio (weight ratio) of (a) / (b) in the propylene polymer composition (a) and the ethylene polymer (b) needs to be in the range of 50/50 to 90/10. It is. If the weight ratio (a) / (b) is less than 50/50, the flame retardancy becomes insufficient, which is not preferable. On the other hand, when the ratio is larger than 90/10, the thermal adhesive property at the time of producing the nonwoven fabric is unfavorably deteriorated.

Further, the total amount (100 parts by weight) of the propylene polymer composition (a) constituting the core and the ethylene polymer (b) constituting the sheath is 0.5 to 9.0 parts by weight based on the amount of the etherified tetrabrominated bisphenol A. It is necessary to adjust to parts by weight. When the amount of the etherified bisbrominated bisphenol A is less than the above lower limit of 0.5 parts by weight, the flame retardancy is insufficient. On the contrary, when it is more than the above upper limit of 9.0 parts by weight, the thermal stability is low. And spinning properties such as coloring and thread breakage are deteriorated, which is not preferable.

Composition (a) of propylene polymer in the present invention
Is based on the fact that propylene-based polymer and etherified bisphenol tetrabromide A, antimony trioxide and metal salts of higher fatty acids are basically contained, and that ethylene-based polymer (b) does not contain flame retardant. However, if necessary, various known stabilizers, coloring agents, antistatic agents, lubricants, nucleating agents, and various kinds of fillers within a range that does not adversely affect the flame retardancy, anti-blooming properties and prevention properties are used. An agent may be added.

A compounding order for preparing the above-mentioned composition (a) of the present invention,
The mixing method is not particularly limited, and the mixing is generally performed using a tumbler-type blender, a V-type blender, a Hensiel mixer, a ribbon mixer, or the like.

Next, in the present invention, the composition (a) of the propylene polymer described above is used as a core, and the ethylene polymer (b)
Is used as a sheath, and the ratio of core / sheath = (a) / (b) (weight ratio) is generally in the range of 50/50 to 90/10. In the production of the composite fiber having such a core / sheath structure, the composition (a) of the core material and the polymer (b) of the sheath material are supplied to separate extruders (with a gear pump). Melt extrusion.
It is obtained by introducing into a composite spinneret and spinning.
The configuration of the core / sheath (weight ratio) in the target conjugate fiber can be adjusted by the rotation speed of the extruder and the gear pump.

(Function and Effect) The conjugate fiber of the present invention has a high degree of flame retardancy and excellent heat fusion at low temperature by using the (a) composition of the specified propylene polymer and the ethylene polymer (b). Adhesion, freely selectable stiffness, excellent spinnability to stably spin fine denier fibers, and high hygiene and safety due to the absence of flame retardant on the fiber surface And is suitable as a raw material for various flame-retardant nonwoven fabrics.

The reason why such a conjugate fiber of the present invention has high flame retardancy is that by using a metal salt of a higher fatty acid together with etherified tetrabrominated bisphenol A, thermal decomposition of the etherified tetrabrominated bisphenol A can be prevented. This is presumed to be attributable to the fact that etherified tetrabrominated bisphenol A can be added to the propylene-based polymer which was suppressed and could not be spun due to the lack of the conventional thermal stability.

In addition, conventional propylene-based polymers were blended with high-temperature decomposable flame retardants represented by decabromodiphenyl oxide. Due to the large diameter, the most suitable spinning method could not stably spin. On the other hand, in the present invention, since the melting point of the etherified tetrabrominated bisphenol A to be blended is lower than the spinning temperature, spinning of fine denier can be stably performed by a general spinning method. Further, the conjugate fiber of the present invention, by blending a flame retardant only in the propylene polymer constituting the core, and not containing the flame retardant in the ethylene polymer constituting the sheath, as a conjugate fiber on the fiber surface An excellent sanitary product without a flame retardant was obtained.

This is because the composition in which a core propylene polymer containing a flame retardant having high flame retardancy called etherified tetrabrominated bisphenol A can be spun, the ethylene polymer contains a flame retardant Even without this, it is considered that a conjugate fiber having sufficient flame retardancy was obtained.

(Examples) Hereinafter, Examples and Comparative Examples will be described in order to specifically explain the present invention, but the present invention is not limited to these Examples.

The spinning method, nonwoven fabric manufacturing method and combustion test in Examples and Comparative Examples were performed as follows.

(1) Spinning method: A propylene-based polymer (hereinafter abbreviated as PP) composition obtained by kneading a predetermined compound is used as a core material, and an ethylene-based polymer (hereinafter abbreviated as PE) composition is also used. Is used as a sheath material and supplied to separate extruders (with a gear pump) to perform melt extrusion, and then introduced into a composite spinneret (number of nozzle holes = 48) to adjust the number of rotations of the extruder and the gear pump. As a result, a composite fiber having a desired core / sheath (weight ratio) of about 10 denier (d) and about 30 denier (d) was obtained.

(2) Fabrication method of nonwoven fabric: After the conjugate fiber obtained by the above-mentioned spinning is stretched as it is or three times, after applying crimp of 18 to 19 pieces / 25 mm by a crimping device of a heating gear type. And cut to a length of about 50 mm. Next, the crimped and cut conjugate fiber is used as a card web, and is thermally welded with a heat roll having a temperature of 115 to 120 ° C. to have a basis weight of about 50.
g / m ² nonwoven fabric.

(3) Combustion test: 30 cm x 4 cm with the long side of the obtained nonwoven sheet in the direction perpendicular to the direction in which the fibers are mainly arranged
And hang it vertically as a sample.
The tip of the burner flame whose length was adjusted to 10 mm by a micro burner of 5 mm was brought into contact with the lower end of the sample, and the tip of the flame was constantly brought into contact with the lower end of the sample while moving the burner according to the deformation of the sample. After contacting the flame for 5 seconds, the flame was removed and the time required for the sample to extinguish was measured to determine the flame retardancy (self-extinguishing time).

Example 1 and Comparative Example 1 A propylene-based polymer shown in Table 1 (hereinafter abbreviated as PP)
And the following blends of the flame retardants 1 to 4 and the like are mixed at a predetermined ratio in a super mixer, and then melt-kneaded at a resin temperature of 210 ° C. in a 50φ pent type extruder to obtain a pellet-like composition. Was.

(Flame retardants 1-4 in the table) In Table 1, the number marked with * is out of the range of the composition (a) specified in the present invention.

Next, using the propylene-based polymer composition and the ethylene-based polymer prepared in Table 1, a composite fiber having a configuration shown in Table 2 was obtained by a predetermined spinning method, and then a nonwoven fabric was manufactured. Flame retardancy was measured. Table 2 shows the measurement results of the spinnability in the production of these composite fibers and the flame retardancy of a nonwoven fabric sample. Note that, in Table-2,
Corresponds to a comparative example. Nos. 15, 16, and 17 used undrawn fibers.

Comparative Example 2 A composite fiber is produced in the same manner as in Example 1. However, as the flame retardant, a compound having no bromine atom in the alkyl group of bisphenol A bis (alkyl ether) tetrabromide was used. Table 3 shows the composition of the core portion, and Table 4 shows the results. * Indicates a comparative example.

Claims (1)

(57) [Claims] 1. A propylene polymer (a) composition containing a flame retardant as described below as a core, and an ethylene polymer (b) containing no flame retardant as a sheath.
The ratio (weight ratio) of (b) is 50/50 to 90/10, and (a) +
Flame-retardant conjugate fiber, characterized in that the amount of etherified bisphenol bisphenol A contained is 0.9 to 9.0 parts by weight based on the total (100 parts by weight) of (b). (A) per 100 parts by weight of a polymer mainly composed of propylene, with respect to etherified tetrabrominated bisphenol A represented by the following general formula: (Wherein R ₁ and R ₂ in the formula are each an alkyl group bonding at least two bromine atoms of the same or different types) of 0.6 to 10 parts by weight, antimony trioxide of 0.5 to 4.0 parts by weight and higher fatty acid Metal salts (however, elements II and I of the periodic table)
Composition containing any of metal salts (II) and (IV)) in an amount of 3 to 30% by weight based on etherified bisphenol A tetrabromide.