JP2000345034A - Flame-retarded polyamide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin composition having high flame retardancy and reduced in mold deposit by including a polyamide resin comprising hexamethyleneadipamide units with a phosphorus-containing flame retardant selected from melamine phosphate and polymelamine phosphate, a phosphoric compound and an inorganic reinforcement in a specified ratio. SOLUTION: This composition contains 30-85 wt.% polyamide resin comprising hexamethyleneadipamide units, 5-40 wt.% phosphorus-containing flame retardant having a particle diameter of 100 μm or below and selected from melamine phosphate and polymelamine phosphate, 0.005-5 wt.% phosphoric compound such as orthophosphoric acid or pyrophosphoric acid, and 5-50 wt.% inorganic reinforcement. It is desirable that the polyamide resin has a relative viscosity in sulfuric acid of 1.5-3.5 and that it is a copolymer comprising 70-98 wt.% polyamide 66 units and 2-30 wt.% polyamide 6I (polyhexanethyleneisophthalamide) units. The inorganic filler used is a fibrous, particulate, or flaky one such as a glass fiber, a carbon fiber, mica, or talc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a flame-retardant polyamide resin composition. In particular, the present invention relates to a flame-retardant polyamide resin composition suitably used for parts such as connectors in the electric and electronic fields and electric parts in the automobile field. In particular, the present invention relates to a flame-retardant polyamide resin composition having extremely high flame retardancy, no generation of highly corrosive hydrogen halide gas during combustion, and excellent moldability with very little mold deposit phenomenon.

[0002]

2. Description of the Related Art Conventionally, polyamide resins have a high mechanical strength,
Because of its excellent heat resistance, automotive parts, machine parts,
Used in fields such as electric and electronic components. In particular, in recent years, the demand for flame retardancy has become increasingly higher in electric and electronic parts applications, and a higher degree of flame retardancy is required than the self-extinguishing property inherent in polyamide resins. For this reason, Underwriters Laboratory UL-94
Numerous studies have been made to improve the flame retardant level that conforms to the V-0 standard. In these, generally, a method of adding a halogen-based flame retardant or a triazine-based flame retardant has been proposed.

For example, addition of a chlorine-substituted polycyclic compound to a polyamide resin (JP-A-48-29846) and addition of a bromine-based flame retardant such as decabromodiphenyl ether (JP-A-47-7134). , Addition of brominated polystyrene (JP-A-51-47044,
175371), addition of brominated polyphenylene ether (Japanese Patent Application Laid-Open No. 54-116054), addition of a brominated crosslinked aromatic polymer (Japanese Patent Application Laid-Open No. 63-317552), brominated styrene-maleic anhydride polymer. Addition of coalescence (JP-A-3-168246) and the like are known.
In particular, a composition in which these halogen-based flame retardants are blended with a polyamide resin reinforced with glass fiber, etc., is used for electrical and electronic parts, especially for connectors mounted or connected to printed laminates due to its high flame retardancy and high rigidity. It has been frequently used for applications. However, halogen-based flame retardants are suspected of generating corrosive hydrogen halide and smoke during combustion and emitting toxic substances, and the use of plastic products containing halogen-based flame retardants has been restricted due to these environmental problems. There is a movement to do. For this reason, halogen-free triazine-based flame retardants have attracted attention and have been studied a lot.

For example, a technology using melamine as a flame retardant (Japanese Patent Publication No. 47-1714), a technology using cyanuric acid (Japanese Patent Application Laid-Open No. 50-105744), and a technology using melamine cyanurate (Japanese Patent Application Laid-Open No. 53-31759
Is well known. Although the non-reinforced polyamide resin composition obtained by these techniques has a high flame retardant level conforming to the UL94V-0 standard, in a composition reinforced with an inorganic reinforcing material such as glass fiber to increase rigidity,
Even when a large amount of a flame retardant is added, there is a problem that cotton ignition occurs at the time of combustion, which does not conform to the UL94V-O standard. In addition, a technique has been proposed in which melamine phosphate, which is an intumescent type flame retardant, is used for a glass fiber reinforced polyamide resin (Japanese Patent Application Laid-Open No. 10-505875). / 16i
Although an nch molded product satisfies the UL94V-0 flame retardant standard, it is difficult to obtain a thin molded product of 1/32 inch that satisfies the UL94V-0 standard due to poor compatibility with a polyamide resin. In addition, workability during extrusion kneading is not only difficult, but also there is a problem that a so-called mold deposit phenomenon occurs in which a flame retardant sublimates during molding and a contaminant adheres to a mold. UL9
The emergence of non-halogen based flame retardant polyamide resins satisfying the 4V-0 standard has been strongly desired.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an enhanced flame retardancy, which has extremely high flame retardancy, does not generate highly corrosive hydrogen halide gas during combustion, and has very little mold deposit phenomenon. It is to provide a polyamide resin composition.

[0006]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that when a specific phosphoric acid compound is blended in a system in which an inorganic reinforcing material, a phosphorus flame retardant and a polyamide resin are combined. It has been found that the object of the present invention can be achieved, and the present invention has been completed based on this finding.

That is, the present invention relates to (a) 30 to 85% by weight of a polyamide resin having a hexamethylene adipamide unit as a main component, and (b) at least one kind selected from melamine phosphate and melamine polyphosphate. The components (a) to (d) are each composed of 5 to 40% by weight of a phosphorus-based flame retardant, (c) 0.05 to 5% by weight of a phosphoric acid compound, and (d) 5 to 50% by weight of an inorganic reinforcing material. A) is a reinforced flame-retardant polyamide resin composition, characterized in that the total amount is 100% by weight.

The polyamide resin (a) used in the present invention
Examples thereof include aliphatic polyamides such as polyamide 66 and polyamide 46, polyamide 6, polyamide 610, polyamide 612, polyamide 11, and polyamide 12, hexamethylene terephthalamide, tetramethylene isophthalamide, hexamethylene isophthalamide, and metaxylylene adipamide. And copolymerized polyamides containing polyamide 66 and an aromatic polyamide containing an aromatic component such as terephthalic acid, isophthalic acid, and xylylenediamine, and a mixed polyamide. In particular, a copolymer of polyamide 66 and polyamide 6I (polyhexamethylene adipamide) and a mixed polyamide thereof are preferable, particularly in view of obtaining high flame retardancy and excellent appearance of the molded product in a thin-walled molded product. Unit 70 ~
A copolymer of 98% by weight and 2 to 30% by weight of a polyamide 6I unit (polyamide 66 / 6I) is most preferable in view of heat resistance, appearance of a molded article, and moldability. These copolymers may be either random copolymers or block copolymers. The polyamide resin may have a molecular weight within a range in which it can be molded, and a polyamide resin having a sulfuric acid relative viscosity of 1.6 to 3.5 according to JIS K6810 has good molding fluidity and high degree of flowability. It is particularly preferable because a high flame retardant level can be maintained.

The phosphorus-based flame retardant (b) used in the present invention
Can be selected from melamine phosphate and melamine polyphosphate, which are melamine adducts obtained from melamine and phosphoric acid or polyphosphoric acid. These flame retardants are compared with triazine flame retardants represented by melamine cyanurate,
When used in combination with inorganic reinforcing materials such as glass fiber,
It has a surprising effect of exhibiting a high flame retardant effect. Particularly, when the phosphorus-based flame retardant is blended with a copolymer of polyamide 66 and polyamide 6I and / or a mixed polyamide resin, a higher degree of flame retardant effect can be exhibited.

The phosphoric acid constituting the melamine phosphate used as a flame retardant in the present invention includes, specifically, orthophosphoric acid, phosphorous acid, hypophosphorous acid, metaphosphoric acid, pyrophosphoric acid,
Examples thereof include triphosphoric acid and tetraphosphoric acid, and an adduct using orthophosphoric acid is particularly preferred because of its high effect as a flame retardant.

The polyphosphoric acid constituting melamine polyphosphate used as a flame retardant in the present invention is a so-called condensed phosphoric acid, and includes chain polyphosphoric acid and cyclic polymetaphosphoric acid. The degree of condensation of these polyphosphoric acids is usually 3
In the present invention, these condensation degrees are not particularly limited.

The phosphorus-based flame retardant of the present invention means a melamine adduct formed from substantially equimolar amounts of melamine and the above-mentioned phosphoric acid or polyphosphoric acid. It may be. Such a melamine adduct is obtained by, for example, forming a mixture of melamine and the above-mentioned phosphoric acid into a water slurry, mixing well to form both adducts in fine particles, and then filtering, washing and drying the slurry. It is a powder obtained by pulverizing the solid material. The mechanical strength of a molded article obtained by molding the finally obtained composition of the present invention, the particle diameter of the melamine adduct in terms of the appearance of the molded article is 100 μm or less, preferably using a powder pulverized to 50 μm or less. good. The use of a powder having a particle size of 0.5 to 20 μm is particularly preferable because not only high flame retardancy is exhibited, but also the strength of a molded article is significantly increased. The melamine adduct does not necessarily need to be completely pure, and some unreacted melamine or phosphoric acid may remain, but the melamine adduct contains 10 to 18% by weight as a phosphorus atom. However, a phenomenon in which a contaminant adheres to a molding die during the molding process is small, and thus it is particularly preferable. These phosphorus-based flame retardants may be used alone or in combination of two or more.

The phosphoric acid compound (c) in the present invention exhibits a surprising effect as a mold deposit inhibitor, and specifically includes orthophosphoric acid, phosphorous acid, hypophosphorous acid, and metaphosphoric acid. , Pyrophosphate, triphosphate,
Tetraphosphates and their polyphosphates are mentioned. In particular, condensed phosphoric acid, such as pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid, are preferably used because of their large effect of suppressing gas generation during molding. Further, these phosphoric acid compounds may be salts with alkali metals or alkaline earth metals.

As the inorganic reinforcing material (d) used in the present invention, glass fiber, carbon fiber, potassium titanate fiber, gypsum fiber, brass fiber, stainless fiber, steel fiber, ceramic fiber, boron whisker fiber, mica, talc,
Fibrous, granular, plate-like, or needle-like inorganic reinforcing materials such as silica, calcium carbonate, kaolin, calcined kaolin, wollastonite, glass beads, glass flakes, and titanium oxide. These reinforcing materials may be used in combination of two or more. Particularly, glass fiber, wollastonite, talc, calcined kaolin and mica are preferably used. The glass fiber can be selected from long fiber type roving, short fiber type chopped strand, milled fiber and the like. It is preferable to use glass fibers that have been surface-treated for polyamide.

In the polyamide resin composition of the present invention comprising the components (a), (b), (c) and (d), the ratio of the main polyamide resin (a) is 30.
It must be in the range of ~ 85% by weight. If it is less than 30% by weight, moldability and mechanical properties are impaired, and if it exceeds 85% by weight, flame retardancy and rigidity may be reduced.

The proportion of the phosphorus-based flame retardant (b) is in the range of 5 to 40% by weight, preferably 10 to 35% by weight. When the amount of the component (b) is less than 5% by weight, the flame retardant effect is not sufficient,
If it exceeds 40% by weight, problems such as generation of decomposition gas at the time of kneading and adhesion of contaminants to a molding die during molding are caused. In addition, it also causes a significant decrease in mechanical properties and a deterioration in the appearance of a molded product.

The proportion of the phosphoric acid compound (c) is from 0.05 to
It is 5% by weight, preferably 0.5-3% by weight. When the amount of the component (c) is less than 0.05% by weight, the effect of suppressing the mold deposit phenomenon at the time of molding is small, and when the amount exceeds 5% by weight, the decomposition of the polyamide resin is accelerated, and there is a concern that the mechanical properties are reduced. There is.

The proportion of the inorganic reinforcing material (d) is 5 to 50% by weight, preferably 10 to 40% by weight. When the content is less than 5% by weight, no manifestation of mechanical strength and rigidity is observed. When the content exceeds 50% by weight, not only the molding processability at the time of extrusion or injection molding is remarkably reduced, but also the effect of quantitative physical property improvement is observed. Absent.

In the present invention, an inorganic flame retardant may be further added within a range that does not adversely affect mechanical properties and moldability. Preferred flame retardant aids include magnesium oxide, magnesium hydroxide, aluminum hydroxide, zinc oxide, zinc sulfide, iron oxide, boron oxide, zinc borate, and the like.

The method for producing the reinforced flame-retardant polyamide resin composition of the present invention is not particularly limited.
A phosphorus-based flame retardant, a phosphoric acid-based compound, and an inorganic filler are kneaded using a conventional single-screw or twin-screw extruder or kneader such as a kneader.
For example, a method of melting and kneading at a temperature of 200 to 350 ° C. may be used.

The reinforced flame-retardant polyamide resin composition of the present invention may contain other components such as a coloring agent such as a pigment or a dye, or a general heat-resistant polyamide resin, as long as the object of the present invention is not impaired. Heat stabilizers such as copper-based heat stabilizers (for example, a combination of copper iodide and copper acetate with potassium iodide and potassium bromide), organic heat-resistant agents such as hindered phenol-based antioxidants, weather resistance Additives such as improvers, nucleating agents, plasticizers, lubricants, antistatic agents, and other resin polymers can be added.

The composition of the present invention can be prepared by injection molding, extrusion molding,
By a known method such as blow molding, connectors, coil bobbins, breakers, electromagnetic switches, holders, plugs,
It is molded into various molded products for electric, electronic and automotive applications such as switches.

[0023]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. The measurement methods used in Examples and Comparative Examples are shown below.

[Measurement Method] (1) Thin-walled flame retardant; UL94 (Under Writers Labo, USA)
ratifications Inc.). The thickness of the test piece was 1/32 inch
And molded by using an injection molding machine (manufactured by Toshiba Machine Co., Ltd .: IS50EP). (2) Relative viscosity of sulfuric acid The relative viscosity with 98% sulfuric acid was measured according to JIS K6810. (3) Mechanical properties Using an injection molding machine (TOSHIBA MACHINE: IS50EP),
A bending test piece (thickness: 3 mm) of STM D790 was formed, and a bending test was performed by a method in accordance with ASTM D790 to determine bending strength and flexural modulus. (3) Mold Deposit Property Using an injection molding machine (manufactured by Toshiba Machine Co., IS50EP), A
A STM D790 bending test piece (thickness: 3 mm) was continuously molded at 50 ° C. at a resin temperature of 280 ° C. and a mold temperature of 80 ° C. After molding, the degree of contamination (mold deposit) on the surface of the mold was visually observed. evaluated. The evaluation criteria are as follows. A: Almost no contamination of the mold was observed. ：: Slight contamination of the mold is observed. ×: Remarkably white contaminants are observed in the mold.

[0025]

Example 1 An equimolar mixture of melamine and orthophosphoric acid was suspended in a 10-fold amount by weight of water, stirred sufficiently at about 100 ° C., and the slurry was filtered to obtain a white cake. Next, the cake was vacuum-dried at 80 ° C. and pulverized to a particle size of 10
A powder of ー 50 μm melamine-phosphoric acid adduct was obtained. The melamine adduct thus obtained (having a phosphorus atom content of 14.
1% by weight) and 25% by weight of polyphosphoric acid (Katayama Chemical: 1)
Grade 66, a polyamide 66 / 6I copolymer (polyamide 6) having 0.5% by weight of sulfuric acid and a relative viscosity of 2.3.
(Copolymerization ratio 80% by weight, melting point 241 ° C.) of 49.5
% By weight and glass fiber [Asahi Fiberglass Co., Ltd. 0
3JA416] using a twin-screw extruder (TEM35, manufactured by Toshiba Machine Co., Ltd.) under a condition of a cylinder set temperature of 260 ° C. and a screw rotation speed of 200 rpm using a twin-screw extruder at a rate of 25 wt%
The polyamide resin, the melamine adduct and the polyphosphoric acid were top-fed, the glass fibers were side-fed and kneaded, taken out into strands, cooled, and granulated with a cutter to obtain pellets. Various characteristics of the obtained pellets were examined by the above-mentioned measuring methods. Table 1 shows the results.

[0026]

Examples 2 to 5 and Comparative Examples 1 and 2 Pellets were obtained in the same manner as in Example 1 except that the mixing ratio of the polyamide resin, melamine-phosphoric acid adduct, polyphosphoric acid and glass fiber was changed to the ratio shown in Table 1. And various characteristics were examined. Table 1 shows the results.

[0027]

EXAMPLE 6 Relative viscosity of sulfuric acid of 2.9 as polyamide resin
Polyamide 66 (manufactured by Asahi Kasei Corporation: Leona 1300),
Except that melamine polyphosphate having an average particle size of about 3 μm [Apinone MPP-A manufactured by Sanwa Chemical Co., Ltd.] was used as a phosphorus-based flame retardant and pyrophosphoric acid (Katayama Chemical: first-class reagent) was used as a phosphate-based compound. Pellets were obtained in the same manner as in Example 1, and various characteristics were examined. Table 2 shows the results.

[0028]

Example 7 Pellets were obtained in the same manner as in Example 6 except that phosphoric acid (Katayama Chemical: first-class reagent) was used as the phosphoric acid compound, and the characteristics were examined. Table 2 shows the results.

[0029]

Comparative Examples 3 and 4 Pellets were obtained in the same manner as in Example 6 except that the mixing ratios of the polyamide resin, melamine polyphosphate, pyrophosphoric acid and glass fiber were as shown in Table 2, and various characteristics were examined. Table 2 shows the results.

[0030]

Comparative Example 5 Sulfuric acid relative viscosity of 2.6 as a polyamide resin
Polyamide 6 [Ube Industries, Ltd .: SF1013A]
A pellet was obtained in the same manner as in Example 6 except that
Various characteristics were investigated. Table 2 shows the results.

[0031]

Comparative Example 6 Pellets were obtained in the same manner as in Example 6 except that trimethyl phosphate (Katayama Chemical: primary reagent) was used instead of pyrophosphoric acid, and various characteristics were examined. Table 2 shows the results.
Shown in

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

Industrial Applicability The composition of the present invention has extremely high flame retardancy even in a thin molded article, furthermore, there is no generation of highly corrosive hydrogen halide gas during combustion, and almost no mold deposit phenomenon occurs during molding processing. It is an excellent molding material that is not recognized and can be used for applications such as home electric parts, electronic parts, and automobile parts.

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Claims (8)

[Claims] (1) 30-85% by weight of a polyamide resin containing hexamethylene adipamide unit as a main component,
(B) 5 to 40% by weight of at least one phosphorus-based flame retardant selected from melamine phosphate and melamine polyphosphate;
(C) a phosphoric acid compound in an amount of 0.05 to 5% by weight, and (d) an inorganic reinforcing material in an amount of 5 to 50% by weight. The total amount of the components (a) to (d) is 100% by weight. An enhanced flame retardant polyamide resin composition. 2. The flame-retardant polyamide resin composition according to claim 1, wherein the polyamide resin (a) has a relative viscosity of sulfuric acid (measured according to JIS K6810) of 1.5 to 3.5. 3. The method according to claim 1, wherein the polyamide resin (a) is polyamide 6
3. The flame-retardant polyamide resin composition according to claim 1, which is a copolymer of polyamide 6 and polyamide 6I (polyhexamethylene isophthalamide) and / or a mixed polyamide thereof. 4. 4. The method according to claim 1, wherein the polyamide resin (a) is polyamide 6
70 to 98% by weight of 6 units and 2 to 30 units of polyamide 6I
3. The flame-retardant polyamide resin composition according to claim 1, wherein the composition is a copolymer with 1% by weight. 5. The flame-retardant polyamide resin composition according to claim 1, wherein the phosphorus-based flame retardant (b) contains 10 to 18% by weight as a phosphorus atom. object. 6. The phosphorus-based flame retardant (b) having an average particle size of 0.
The thickness is 5 to 20 μm.
6. The flame-retardant polyamide resin composition according to 3, 4 or 5. 7. The method according to claim 1, wherein said (c) phosphate compound is at least one compound selected from phosphoric acid, pyrophosphoric acid and polyphosphoric acid. 7. The flame-retardant polyamide resin composition according to 6. 8. The method according to claim 1, wherein the inorganic reinforcing material (d) is at least one reinforcing material selected from the group consisting of glass fiber, wollastonite, talc, calcined kaolin, and mica. The flame-retardant polyamide resin composition according to 3, 4, 5, 6, or 7.