JP2001200136A - Flame retarded polyacetal resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame retarded polyacetal resin composition in a field in which the use of the polyacetal resin is limited up to now by imparting a flame retardancy to the polyacetal resin while maintaining excellent physical properties of the resin. SOLUTION: This flame retarded polyacetal resin composition is obtained by mixing at least one kind selected from a lignin and a cellulose, at least one kind of flame retardant selected from red phosphorus and phosphoric salts, and a heat stabilizer into the polyacetal resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyacetal resin composition having excellent flame retardancy. More specifically, the present invention relates to a flame-retardant resin composition having excellent heat stability and mechanical properties.

[0002]

2. Description of the Related Art Polyacetal resins have been used in a wide range of fields, mainly automotive parts and OA equipment parts, as engineering resins having balanced mechanical properties and excellent moldability. However, at present, the use is restricted in applications requiring flame retardancy because of being flammable. Conventionally, various methods have been proposed for imparting flame retardancy to polyacetal resins. For example, Japanese Patent Publication No. 43-22676 discloses a method of adding ammonium phosphate, and Japanese Patent Publication No. 53-31899 discloses a method of adding guanidine phosphate, melamine and polyammonium ammonium to a polyacetal resin. JP-A-9-324105 describes a method of adding ammonium polyphosphate having a particle size of 30 μm or less alone or in combination with ammonium polyphosphate and melamine.

[0003] However, in the above method, the flame retardancy is insufficient. A method of adding flame retardancy by adding red phosphorus and melamine to a polyacetal resin is disclosed in
As described in JP-A-8-7044, it is necessary to add a large amount of triazine compounds such as melamine, guanidine phosphate and cyanoguanidine in order to obtain sufficient flame retardancy. As with the combination of melamine, the physical properties of the polyacetal resin are significantly reduced. Further, as another method for imparting flame retardancy to a polyacetal resin, JP-A-3-21747 discloses 10-7.
A method of blending 0% by weight of pulp has been proposed,
Insufficient flame retardancy. On the other hand, JP-B-7-33461 and JP-B-7-45611 are disclosed as conventional techniques for adding cellulose. However, these are added in an amount of 0.05 to 5% by weight and the heat of the polyacetal resin is reduced. It is used as a stabilizer and is insufficient to satisfy flame retardancy, and there is no description about flame retardancy.
As described above, it is very difficult to impart flame retardancy to polyacetal resin due to its resin properties, and at present, there is no practically usable composition at this stage.

[0004]

By imparting flame retardancy while maintaining the excellent physical properties of the polyacetal resin,
Provide materials for previously restricted areas.

[0005]

The present inventors have conducted intensive studies on flame-retardant polyacetal resins. As a result, the incorporation of lignin or cellulose and red phosphorus or phosphate into the polyacetal resin allows the flame retardancy of the polyacetal resin to be reduced. The inventors have found that the invention can be achieved, and have completed the present invention.
That is, the present invention provides (A) a polyacetal resin, (B) at least one selected from lignin or cellulose,
A flame-retardant polyacetal resin composition comprising (C) at least one flame retardant selected from red phosphorus or phosphate and (D) a triazine compound.

Hereinafter, the present invention will be described in detail. The polyacetal resin of the present invention is a homopolymer obtained by homopolymerizing a formaldehyde monomer or its trimer trioxane or tetramer tetraoxane, and blocking the terminal with an ester terminal or an ether terminal, or the trioxane or tetraoxane and ethylene oxide. A copolymer containing 0.1 to 20% by weight of an oxyalkylene unit having 2 to 8 carbon atoms obtained by copolymerizing a cyclic ether such as 1,3-dioxolane, and a heterogeneous component segment such as polyoxyalkylene are introduced. There are no particular restrictions on the block polymer, the branched polymer and the like, but a polyacetal copolymer is preferred.

Lignin and cellulose used as the component (B) of the present invention have an effect of greatly improving the flame retardancy of a polyacetal resin containing a flame retardant, which is an important point of the present invention. When only the flame retardant is added to the polyacetal resin, if the concentration of the flame retardant is extremely increased, the flame retardancy is improved, but at the same time, the mechanical properties are greatly reduced. On the other hand, when lignin and cellulose are added, the concentration of the flame retardant can be reduced, and a decrease in mechanical properties can be suppressed.

First, lignin, one of the components (B), is obtained as a by-product during pulp production. That is, wood is cellulose and lignin using calcium sulfite aqueous solution,
It is separated into hemicelluloses and the like. At this time, lignin and hemicelluloses which dissolve in water can be used in the present invention. However, the lignin obtained at this time has a pH of 2 to 6, and when added to a polyacetal resin, reduces the thermal stability. Therefore, in the present invention, it is preferable to use lignin whose pH is adjusted to 6 to 10 by further reacting with sodium, potassium or the like. In the present invention, those obtained by treating this lignin to increase the lignin concentration, those whose molecular weight has been adjusted, those whose impurities have been removed, and the like can be used. Lignin is usually obtained as an aqueous solution, and there is also a powder obtained by dehydration, spray drying or the like. In the present invention, powdered lignin is suitable, and in this case, the particle size of lignin is preferably 200 microns or less.

[0009] Examples of cellulose include wood, paper, and cotton linter. Some of these celluloses usually contain 1 to 30% of lignin or hemicellulose, but in the present invention, the above cellulose can be used regardless of the presence or absence of lignin or hemicellulose. In the present invention, use of cotton linter is particularly preferred. These celluloses are added to the polyacetal resin after processing such as pulverization, but are not particularly limited. Preferably the particle size is 0.5-10 μm,
Cellulose ground to a length of 10 to 5000 μm is added.

In the present invention, the concentration of lignin or cellulose in the total composition is 0.1 to 30% by weight, preferably 1 to 20% by weight. If the concentration of lignin or cellulose is less than 0.1% by weight, the flame retardancy becomes insufficient, and if the concentration is 30% by weight or more, physical properties decrease, which is not preferable. As the red phosphorus used for the component (C) of the present invention, a common commercially available red phosphorus can be used. Red phosphorus is self-igniting at about 260 ° C. Normal red phosphorus, red phosphorus whose auto-ignition temperature is raised to 300 ° C or more by coating with inorganic substances such as magnesium hydroxide and aluminum hydroxide, and resin, and various oils Although there are treated red phosphorus and the like, they can be used together in the present invention and are not particularly limited. Preferably, red phosphorus which is coated with an inorganic substance and a resin and has an auto-ignition temperature of 300 ° C. or higher is mentioned, and red phosphorus which is double-coated with an inorganic substance and a resin is particularly preferable. Specific examples of red phosphorus include NOVARED 120, 140, and F5 manufactured by Rin Kagaku Kogyo KK.

The phosphate of the component (C) of the present invention includes ammonium phosphate, ammonium polyphosphate, ammonium phosphate, guanidine phosphate, melamine phosphate and melamine polyphosphate. Is particularly preferably ammonium polyphosphate.

As the ammonium polyphosphate, an ordinary commercially available one can be used. Ammonium polyphosphate is synthesized by reacting ammonia with polyphosphoric acid. As the polyphosphoric acid, a type 1 having a linear structure and a type 2 having a network structure are known. Ammonium polyphosphate starts to decompose at around 200 ° C., and polyphosphoric acid and ammonium are generated at this time. Ammonium polyphosphate made from type 2 polyphosphoric acid is less than ammonium polyphosphate made from type 1 polyphosphoric acid. Decomposition near 200 ° C is small and stable. When ammonium polyphosphate is added to the polyacetal resin, the polyacetal resin is decomposed by the polyphosphoric acid, resulting in a problem that thermal stability is reduced and formaldehyde adheres to a mold (MD) during molding. Therefore, in the present invention, an ammonium polyphosphate made from a type 2 polyphosphoric acid having excellent stability particularly at around 200 ° C. is preferable. It is also possible to use ammonium polyphosphate obtained by coating ammonium polyphosphate with melamine, a melamine resin or the like. Specific examples of ammonium polyphosphate include Terage C6 manufactured by Chisso Corporation.
0, C70, C80, Sumisafe P manufactured by Sumitomo Chemical Co., Ltd., Hostaframe AP42 manufactured by Clariant Co., Ltd.
2, AP462 and the like. Among these, Terage C60, C70, and C using type 2 polyphosphoric acid as a raw material
80 and Clariant Co., Ltd. Hostaframe AP42
2, AP462 is more preferred in the present invention.

The concentration of the red phosphorus or phosphate of the present invention in the total composition is 1 to 50% by weight. When using red phosphorus,
The concentration of red phosphorus is from 1 to 20% by weight, preferably from 3 to
15% by weight. On the other hand, the concentration when using a phosphate is 1 to 50% by weight, preferably 5 to 30% by weight. When the concentration of red phosphorus or phosphate is 1% by weight or less, flame retardancy is insufficient, and when the addition amount is 50% by weight or more, mechanical properties, particularly elongation and impact resistance are undesirably reduced. In the present invention, at least one kind of the red phosphorus or the phosphate is added as a flame retardant, but there is no problem if they are used in combination. The particle size of red phosphorus and phosphate is usually 1
The particles having a particle diameter of 1 μm to 50 μm are not particularly limited in the present invention.

Specific examples of the triazine compound used in the component (D) of the present invention include melamine, benzoguanamine, melam, melem, melon, 1,2-bis (3,
5-diamino-2,4,6-triazinyl) ethane,
1,3-bis- (3,5-diamino-2,4,6-triazinyl) propane; and melamine is particularly preferred. Melamine has an effect as a carbonization layer formation promoter during combustion, and also acts as a heat stabilizer when the flame retardant is ammonium polyphosphate.

The concentration of these triazine compounds in the total composition is 0.1 to 20% by weight. When the concentration of the triazine compound is less than 0.1% by weight, the effect of promoting the formation of the carbonized layer is reduced. The preferred concentration of the triazine compound is 1 to 10% by weight. Further, conventionally known additives may be added to the composition of the present invention in order not to impair the purpose of the present invention in order to further impart desired properties according to the purpose. For example, a hindered phenol-based antioxidant, a release agent such as ethylene bisamide, a lubricant, an antistatic agent, an ultraviolet absorber, a light stabilizer and the like can be added. The composition of the present invention can be obtained by using a conventional melt kneader. Examples of the melt kneader include a single screw extruder, a twin screw extruder, and a kneader. The components (B), (C) and (D) of the present invention are supplied to a melt kneader together with the polyacetal resin and melted and kneaded, but the addition method and the kneading method are not particularly limited. .

[0016]

The present invention will be described in detail with reference to the following examples. The components used in Examples and Comparative Examples of the present invention are as follows. Polyacetal resin; Tenac (trademark) C4520, manufactured by Asahi Kasei Kogyo Co., Ltd., MI = 10 g / 10 minutes Lignin; Nippon Paper Industries Co., Ltd., Pearlrex NP, P
H = 8.5 Cotton linter; Bemberg, manufactured by Asahi Kasei Kogyo Co., Ltd., was dried and then pulverized to a diameter of 10 μm and a length of 1000 μm.

Red Phosphorus (1); Rinno Kagaku Kogyo Co., Ltd., Nova Red F5, double coating of inorganic material and resin, average particle size = 5 μm Red Phosphorus (2); Red 14
0, without resin coating, average particle size = 40 μm ammonium polyphosphate (1); manufactured by Chisso Corporation, Terage C60, with resin coating, average particle size = 7.5 μm ammonium polyphosphate (2); Clariant Co., Ltd.
Manufactured by Hostaframe AP422, average particle size = 15 μm melamine; manufactured by Nissan Chemical Industries, Ltd., average particle size = 5 μm Further, the method for evaluating the flame retardancy of Examples and Comparative Examples of the present invention is as follows. (1) Flame retardancy: Measurement was carried out using a 127 × 12.7 × 3.5 mm test piece in accordance with UL Flame Resistance Test Standard (UL94). The evaluation was performed based on the total burning time (seconds) and the presence / absence of dripping of the five test pieces during the first and second flame-contacting operations in a total of 10 times.

[0018]

Example 1 83% by weight of polyacetal resin, 3% by weight of cotton linter as cellulose, 10% by weight of Nova Red F5 (trade name) manufactured by Rin Kagaku Kogyo Co., Ltd. as flame retardant, and 4% by weight of melamine as heat stabilizer % 2
Pelletizing was performed at 190 ° C. using a screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.). 200 pellets
Molding machine (Toshiba Machine Co., Ltd., IS-
100E) to obtain a test piece of 127 × 12.7 × 3.5 mm, left in a room controlled at a temperature of 23 ° C. and a humidity of 50% for 2 days, and evaluated the flame retardancy according to the UL flame resistance test standard. did. Table 1 shows the evaluation results.

[0019]

Examples 2 to 17 Pelletizing and evaluation were conducted in the same manner as in Example 1 except that the types and concentrations of lignin or cellulose, a flame retardant and a heat stabilizer were changed. Table 1 shows the results
Shown in

[0020]

Comparative Examples 1 to 10 Pelletizing and evaluation were conducted in the same manner as in Example 1 except that the types and concentrations of lignin or cellulose, a flame retardant and a heat stabilizer were changed. Table 2 shows the results
Shown in

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

According to the present invention, it is possible to impart flame retardancy while maintaining the excellent physical properties of a polyacetal resin, and to provide a material to a field where its use has been conventionally restricted. became.

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Claims (10)

[Claims] (A) a polyacetal resin, (B) at least one selected from lignin or cellulose,
A flame-retardant polyacetal resin composition comprising (C) at least one flame retardant selected from red phosphorus or phosphate and (D) a triazine compound. 2. The method according to claim 1, wherein said lignin is a 5% aqueous solution.
The resin composition according to claim 1, wherein the pH is from 10 to 10. 3. The resin composition according to claim 1, wherein said cellulose is cotton linter. 4. The resin composition according to claim 1, wherein the concentration in the total composition of at least one selected from the group consisting of lignin and cellulose is 0.1 to 30% by weight. 5. The method according to claim 1, wherein the red phosphorus or the phosphate is 1 to 50 μm.
The resin composition according to claim 1, wherein the average particle size is 6. The resin composition according to claim 1, wherein the red phosphorus is coated with an inorganic substance and / or a resin. 7. The resin composition according to claim 1, wherein the phosphate is ammonium polyphosphate, and the ammonium polyphosphate comprises a type 2 polyphosphoric acid and ammonia. 8. The method according to claim 1, wherein the concentration of at least one flame retardant selected from the group consisting of red phosphorus and phosphate in the total composition is 1 to 50% by weight. The resin composition as described in the above. 9. The resin composition according to claim 1, wherein the triazine compound is melamine. 10. The resin composition according to claim 1, wherein the concentration of the triazine compound in the total composition is 0.1 to 20% by weight.