JP2003105659A - Flame-retardant polyamide nonwoven fabric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a nonwoven fabric having excellent flame retardance and improved formability, especially a nonwoven fabric which provides sufficient flame retardance even without using a halogen-based flame retardant, has high safety and high value of utilization as a flame-retardant interior material for vehicles, airplanes and architectural structures. SOLUTION: This nonwoven fabric is obtained by using a polyamide resin composition prepared by compounding 98-80 parts wt. of a polyamide resin with 2-20 parts wt. of a triazine-based flame retardant without using a halogen- based flame retardant and has <=25 μm average particle diameter of the triazine- based flame retardant dispersed in the filament constituting the nonwoven fabric.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a non-woven fabric using a specific polyamide resin composition having excellent flame retardancy. Specifically, it is an object of the present invention to provide a non-woven fabric excellent in flame retardancy, which is highly safe in an environment where generation of dioxins and toxic gases is small.

[0002]

2. Description of the Related Art Nonwoven fabrics are widely used for interiors of automobiles, railroad vehicles, aircrafts, buildings and the like. By the way, conventionally, the materials used for the nonwoven fabric have been polyolefin resins represented by polyethylene and polypropylene, polyamide resins, polyester resins and the like. In recent years, there has been a demand to make such interior materials flame-retardant in order to prevent fires, and it does not use halogen-based flame-retardants, which are said to pose the risk of environmental pollution or health problems, and has excellent flame-retardant properties. There has been a demand for non-woven fabrics. However, the polyolefin resin
As a method of flame retarding without using a halogen-based flame retardant, it has been proposed to blend magnesium hydroxide or urea, but the blending amount is 40 parts by weight or more based on 100 parts by weight of the polyolefin resin. In that case, yarn breakage frequently occurs in the non-woven fabric manufacturing process, resulting in a marked decrease in productivity. In addition, a method for making a polyester resin flame-retardant without using a halogen-based flame retardant has not been proposed yet. On the other hand, no flame-retardant safe non-woven fabrics made of polyamide resin have practically sufficient performance to date.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-woven fabric which does not contain a halogen compound and is highly flame-retardant and highly safe for the environment.

[0004]

The present invention has been made to solve the above-mentioned problems, and the gist thereof is to add 98 to 80 parts by weight of a polyamide resin to a triazine-based flame retardant 2
A triazine-based flame retardant having an average particle size of 25 μm or less, wherein the triazine-based flame retardant is made of a polyamide resin composition containing 20 to 20 parts by weight and does not use a halogen-based flame retardant and is dispersed in filaments constituting a nonwoven fabric. It exists in a non-woven fabric characterized by being present.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. Polyamide Resin As the polyamide resin in the present invention, a lactam having three or more membered rings, a polymerizable ω-amino acid, or a polyamide obtained by polycondensation of a dibasic acid and a diamine can be used. Specifically, polymers such as ε-caprolactam, aminocaproic acid, enanthlactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone and α-piperidone, hexamethylenediamine, nonamethylenediamine,
Undecamethylenediamine, dodecamethylenediamine,
Diamines such as metaxylylenediamine, terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecane dibasic acid, a polymer obtained by polycondensation with a dicarboxylic acid such as glutaric acid, or a copolymer thereof, for example, Polyamide (nylon) 4, 6, 7, 8, 11, 1
2, 66, 69, 610, 611, 612, 6/66,
Polymers and copolymers of aliphatic polyamide such as 6/12,
Examples thereof include aromatic polymers and copolymers such as 6T, 6 / 6T, 6T / 6I, and MXD6, and it is also possible to use a plurality of these polyamide resins in combination.

The end of the polyamide resin in the present invention is
It may be encapsulated with a carboxylic acid or amine, and a polyamide resin encapsulated with a carboxylic acid or amine having 6 to 22 carbon atoms is particularly desirable. Specific examples of the carboxylic acid used for sealing include aliphatic monocarboxylic acids such as caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, and behenic acid. Examples of amines include aliphatic primary amines such as hexylamine, octylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, and behenylamine. The amount of carboxylic acid or amine used for sealing is 30 μe
About q / g is preferable.

The polyamide resin suitable for the present invention preferably has a degree of polymerization within a certain range, that is, a relative viscosity. A preferred relative viscosity is 2.0 to 4.0, and more preferably 2.0 to 3.0, as measured according to JIS K6810 in 98% sulfuric acid at a concentration of 1% and a temperature of 25 ° C. If the relative viscosity is lower than 2.0, the melt viscosity becomes too low, which makes it difficult to manufacture a nonwoven fabric and also lowers the mechanical strength. If the relative viscosity is higher than 4.0, the melt fluidity will be impaired, which is not preferable. In the present invention, particularly preferred polyamides are nylon 6, copolymer nylon 6 /, in view of flame retardancy, mechanical strength and moldability.
Examples include 66 and nylon 66.

Triazine Flame Retardant Examples of the triazine flame retardant in the present invention include compounds represented by the following general formula (1) or (2), melamines and melamine cyanurate.

[0009]

[Chemical 1]

(In the formula, each of R ^{1 to} R ^{6 represents} a hydrogen atom or an alkyl group.) Specific examples of the compound represented by the general formula (1) are:
Examples thereof include cyanuric acid, trimethylcyanurate, triethylcyanurate, tri (n-propyl) cyanurate, methylcyanurate and diethylcyanurate.
Specific examples of the compound represented by the general formula (2) include:
Examples thereof include isocyanuric acid, trimethyl isocyanate, triethyl isocyanate, tri (n-propyl) isocyanurate, diethyl isocyanurate, methyl isocyanurate and the like.

Examples of melamines include melamine, melamine derivatives, compounds having a structure similar to melamine, and melamine condensates. Specific examples of melamines include, for example, melamine, ammelide, ammeline,
Formoguanamine, guanylmelamine, cyanomelamine, arylguanamine, melam, melem, melon and the like can be mentioned.

Examples of melamine cyanurates include equimolar reaction products of cyanuric acid and melamines. Also,
Some of the amino groups or hydroxyl groups in the melamine cyanurates may be substituted with other substituents. Among them, melamine cyanurate can be obtained, for example, by mixing an aqueous solution of cyanuric acid and an aqueous solution of melamine, reacting at 90 to 100 ° C. under stirring, and filtering the generated precipitate, which is a white solid. It is preferable to use a commercially available product as it is or crush it into a fine powder before use.
The triazine-based flame retardant is preferably a compound having two or more triazine rings in one molecule, specifically, melamine cyanurate, melam, melem, melon and the like. Since these have a high heat resistant temperature, they are less likely to cause yarn breakage due to generation of decomposition gas at the molding temperature, and are suitable for the production of nonwoven fabrics. In particular, since an inconvenience such as blooming in which a decomposed product is raised on the surface of a molded product does not occur, an equimolar reaction product of cyanuric acid and melamines is more preferable.

The triazine-based flame retardant is usually a state in which fine powder of submicron order is aggregated. Therefore, it is necessary to appropriately select the particle size of the aggregate of the triazine-based flame retardant dispersed in the filament depending on the type of the flame retardant used and the diameter of the filament constituting the nonwoven fabric so that the desired performance can be obtained. There is. That is, in the present invention, the average particle diameter of the aggregate of the triazine-based flame retardant dispersed in one filament (monofilament: hereinafter referred to as “filament”) constituting the nonwoven fabric (in the present invention, “number” It is necessary that the average particle size ”is 25 μm or less. This average particle size is preferably 5
It is less than μm. The average particle size is "1 constituting the nonwoven fabric.
The average particle size of the aggregate of the flame retardant dispersed in the filament of the book ”is shown.
It is smaller than the diameter of the filament of the book, but more preferably 1/2 or less of the diameter.

The triazine-based flame retardant can break up the agglomerates to some extent in the step of blending with the polyamide resin and the step of manufacturing the non-woven fabric, but filament formation is stable,
That is, in order to pass through the non-woven fabric manufacturing process, it is preferable to crush and use it in advance. Specifically, it is preferable to use it with an average particle diameter of 25 μm or less before compounding with a polyamide resin.

The average particle size of the triazine-based flame retardant dispersed in the filament can be measured by, for example, cutting the filament, removing the triazine-based flame retardant from the cross section, and observing the traces of the triazine-based flame retardant. You can know by observing. The average particle size of the triazine-based flame retardant before being added to the resin composition is an existing powder particle size measuring device, for example, a sedimentation flowmeter or a laser diffraction type particle size meter,
It can be measured with an ordinary optical microscope. The compounding amount of the triazine flame retardant is 2 to 20 parts by weight with respect to 98 to 80 parts by weight of the polyamide resin. If the blending amount of the triazine-based flame retardant is less than 2 parts by weight, the flame retardancy tends to decrease, and if it exceeds 20 parts by weight, it is cut off in the nonwoven fabric manufacturing step, which is not preferable. The amount of the triazine-based flame retardant compounded is preferably 3 to 20 parts by weight.

The triazine-based flame retardant may be added to the polyamide resin by any known means at any stage immediately before the production of the nonwoven fabric. As the simplest method, a method of pelletizing a polyamide resin and a triazine flame retardant by melt mixing extrusion is adopted. Also, a resin composition in a desired ratio can be obtained by preparing a master pellet in which a polyamide resin is preliminarily kneaded with a triazine-based flame retardant in an amount larger than a predetermined amount, and dry blending the master pellet with the polyamide resin for dilution. . Further, the desired resin composition can be obtained by dry blending the polyamide resin and the triazine flame retardant, pelletizing by melt mixing extrusion, and dry blending the heat stabilizer. Further, a pigment, a dye, a filler, a nucleating agent, a releasing agent, a stabilizer, an antistatic agent and other well-known additives may be added to the resin composition of the present invention and kneaded. Further, in the polyamide resin composition of the present invention, a thermoplastic resin other than the polyamide resin can be added within a range that does not impair the effects of the present invention. The nonwoven fabric of the present invention is J
It has a flame retardancy of more than 27 as the oxygen index according to the measuring method according to IS K7201. Since the oxygen index of the polyamide resin changes depending on its water absorption, it can be measured after the condition is adjusted at 23 ° C. and 65% RH for 24 hours or more. Oxygen index is the oxygen concentration (% by volume) required for the sample to continue combustion.
If the oxygen index is 22 or more, it means that the material is a self-extinguishing material that cannot continue combustion with the oxygen concentration in the atmosphere.

Examples of the method for producing the nonwoven fabric of the present invention include spun bond method, melt blown method, spun lace method, needle punch method, stitch bond method and the like. In particular, the spun bond method is melted by using an extruder. A web is formed from a fiber group formed by spinning a resin, and then bonding is performed, which is a highly productive method capable of integrated production in one line, which is preferable. The fineness of one filament constituting the nonwoven fabric is 0.5 to 50 dtex (0.45 to 45 dtex).
Denier) is preferable, and when converted to the diameter of the filament (assuming that the cross-sectional shape is a circle), it is usually 7.5 to
This is a range of 75 μm. Further, the filament may have a circular cross section or an irregular shape other than that, and may have voids inside or a bulky shape.

[0018]

EXAMPLES Examples of the present invention will be described in detail below, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. <Polyamide 6 resin> As the polyamide 6 resin, Novamid (registered trademark) 1015J (relative viscosity: 3.0) manufactured by Mitsubishi Engineering Plastics Co., Ltd. was used. <Production of Copolyamide 6/66 Resin> A 50% aqueous solution of a salt of adipic acid and hexamethylenediamine (hereinafter abbreviated as AH salt) and ε-caprolactam (hereinafter abbreviated as CL) up to 100 ° C., respectively. The heated mixture was mixed so that 15 parts by weight of AH salt and 85 parts by weight of CL were mixed, and then charged in a 200 liter autoclave and 270 at an internal pressure of 13 kg / cm ² (1275 kPa).
After the temperature was raised to 0 ° C, the internal temperature was kept at 245 ° C, the pressure was gradually reduced with stirring at 0.5 kg / cm ² (49 kPa), and the stirring was stopped when the power reached a predetermined value. Thereafter, nitrogen was introduced to restore the pressure, and the strand was extracted and pelletized. The unreacted material was extracted and removed using boiling water, and then dried. The copolyamide 6/66 resin thus obtained had a relative viscosity of 3.0 and a melting point of 200 ° C.

<Triazine Flame Retardant> Melamine Cyanurate A: Melamine cyanurate (trade name: MCA-C0) manufactured by Mitsubishi Chemical Co., Ltd. was pulverized with a tabletop ball mill.
The crushed product had an average particle size of 2.5 μm when measured with an automatic sedimentation particle size analyzer manufactured by Shimadzu Corporation. Melamine cyanurate B: Melamine cyanurate (trade name: MCA-C0) manufactured by Mitsubishi Chemical Corporation was classified with a 200-mesh sieve. The average particle size of this classified product was 80 μm when measured with an automatic sedimentation particle size analyzer manufactured by Shimadzu Corporation.

<Production of Polyamide Resin Composition> Polyamide 6 resin or copolymerized polyamide 6/66 resin as a polyamide resin, and a triazine flame retardant are blended in a ratio shown in Tables 1 and 2, and a cylinder diameter of 30 mm is provided with a vent. Using a twin-screw extruder (manufactured by Japan Steel Works, trade name: TEX30),
Melt kneading was performed at a resin temperature of 240 to 260 ° C. to obtain polyamide resin composition pellets. Then, the obtained polyamide resin composition pellets were -10 at 120 ° C. under a gauge pressure.
After drying under reduced pressure of 1 kPa for 6 hours, the sample was molded.

The polyamide resin material was evaluated according to the following criteria. (1) Relative viscosity Based on JIS K6810, the viscosity was measured at 25 ° C. in 98% sulfuric acid concentration of 1%. (2) Take out 10 filaments from the nonwoven fabric formed by molding the average particle diameter of the triazine-based flame retardant dispersed in the filaments constituting the nonwoven fabric,
It was embedded in an epoxy resin into a cylindrical shape having a major axis of 2 mm and a length of 5 mm. A notch was made on one side surface of the cylindrical epoxy resin-embedded sample with a razor, and the sample was broken under liquid nitrogen. The epoxy resin-embedded filament including the obtained cross section was subjected to ultrasonic cleaning in an n-hexane bath at room temperature for 30 minutes to remove the triazine-based flame retardant from the cross section. Then, platinum was vapor-deposited on the cross section, and SEM observation was performed at a magnification of 5000 times to measure the major axis of the removal trace of the triazine-based flame retardant, and the 100-point average was taken as the average particle diameter. (3) Oxygen index molded non-woven fabric was cut into a width of 10 mm and a length of 100 mm, left for 24 hours or longer in a room at 23 ° C. and 65% RH, and then using a D-type candle combustion tester manufactured by Toyo Seiki Co., Ltd. Then, the oxygen index was measured according to JIS K7201.

Examples 1 and 2 The polyamide resin compositions shown in Table 1 were equipped with a gear pump and a spunbonding die (nozzle diameter 0.4 mm, 120 holes) at the tip, cylinder diameter 30 mm, L / D =
It is put into a single-screw extruder having a full flight screw of 27, melted at a resin temperature of 260 ° C., passed through an air-cooled chamber, a spinning traction device, and a fiber opening device, accumulated on a collecting conveyor to form a web, Passing between the heating embossing roll and the smooth roll, filament diameter about 30μm, basis weight 30g
A nonwoven fabric of / m ² was obtained. The filament was taken out from the obtained non-woven fabric, the dispersed particle size of the triazine-based flame retardant was measured, and the oxygen index was measured on the sample cut from the non-woven fabric. Comparative Examples 1-3 Nonwoven fabric molding was tried in the same manner as in Examples 1 and 2, but spinning
Non-woven fabric samples could not be obtained due to frequent yarn breakage during the drawing process.

[0023]

[Table 1]

[0024]

According to the present invention, it is possible to provide a non-woven fabric having excellent flame retardancy and good moldability. Further, since sufficient flame retardancy can be obtained without using a halogen-based flame retardant, it is highly safe and therefore highly useful as a flame retardant interior material for vehicles, aircraft and buildings.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiji Morimoto             5-6-2 Higashi-Hachiman 5-2, Hiratsuka City, Kanagawa Prefecture             Ryo Engineering Plastics Stock Association             Company Technology Center (72) Inventor Morio Tsunoda             5-6-2 Higashi-Hachiman 5-2, Hiratsuka City, Kanagawa Prefecture             Ryo Engineering Plastics Stock Association             Company Technology Center F-term (reference) 4J002 CL001 EU186 FD136 GK00                 4L035 AA05 FF05 GG03 JJ21 LC02                 4L047 AA23 AA29 AB10 BA08 BA23                       EA06

Claims (5)

[Claims] 1. A polyamide resin composition comprising 98 to 80 parts by weight of a polyamide resin and 2 to 20 parts by weight of a triazine-based flame retardant, wherein a halogen-based flame retardant is not used in a filament constituting the nonwoven fabric. An average particle size of the dispersed triazine-based flame retardant is 25 μm or less. 2. The non-woven fabric according to claim 1, wherein the triazine-based flame retardant dispersed in the filaments of the non-woven fabric has an average particle size of less than 5 μm. 3. The nonwoven fabric according to claim 1, wherein a polyamide resin composition containing a polyamide resin having a relative viscosity of 2.0 to 4.0 is used. 4. The oxygen index according to the measuring method according to JIS K7201 is larger than 27.
The nonwoven fabric according to any one of items 1 to 3. 5. The nonwoven fabric according to claim 1, wherein the triazine flame retardant is an equimolar reaction product of cyanuric acid and melamines.