WO2021044880A1

WO2021044880A1 - Flame-retardant polyamide resin composition and molded article comprising same

Info

Publication number: WO2021044880A1
Application number: PCT/JP2020/031721
Authority: WO
Inventors: 和樹岩村; 信宏吉村
Original assignee: 東洋紡株式会社
Priority date: 2019-09-02
Filing date: 2020-08-21
Publication date: 2021-03-11
Also published as: TW202112966A; JPWO2021044880A1

Abstract

[Problem] To provide a flame-retardant polyamide resin composition which is ideal for a molded component having a thin-walled portion such as a hinge portion, and which has excellent flame retardancy while also having excellent heat discoloration resistance and moldability and imparting an excellent snap-fitting ability to the obtained component. [Solution] A flame-retardant polyamide resin composition which contains 97.5-94 parts by mass of a polyamide resin (A) and 2.5-6 parts by mass of melamine cyanurate (B), the polyamide resin (A) containing 50-80 parts by mass of a polyamide 66 resin (A-1) and 15-45 parts by mass of a polyamide 6 resin (A-2), and which contains, relative to a total of 100 parts by mass of components (A) and (B), 0.01-1 parts by mass of a phosphorus antioxidant (C), 0.01-1 parts by mass of a hindered phenolic antioxidant (D), and 0.05-1 parts by mass of a fatty acid metal salt lubricant (E).

Description

Flame-retardant polyamide resin composition and molded products made from it

The present invention relates to a non-halogen-based flame-retardant polyamide resin composition. More specifically, the present invention relates to a non-halogen-based flame-retardant polyamide resin composition having high flame retardancy, good toughness, and excellent heat-resistant discoloration.

Polyamide resins are used in various fields such as electrical / electronic parts and automobile parts by utilizing their excellent mechanical properties, electrical properties, chemical resistance and the like. In these fields, melamine cyanurate is used as a flame retardant when it is required to impart flame retardancy with a non-strengthening and non-halogen flame retardant (for example, Patent Documents 1 and 2).
However, melamine cyanurate has poor dispersibility in the polyamide resin, the mechanical properties of the polyamide resin deteriorate, bleeding when the blending amount is large, and it is easily decomposed into melamine and cyanuric acid by thermal decomposition and sublimated, and sublimated melamine. In addition, due to the influence of cyanuric acid, silver is generated on the surface of the molded product during the molding process, and the surface of the mold is easily contaminated.

In recent years, various demand levels for electrical / electronic parts, automobile parts, etc. have become high, and flame retardancy is required to be V-0 level with a UL94 thickness of 0.4 mm for parts having thin-walled parts such as hinge parts. In both cases, there is no bleeding of flame retardants, and higher levels of heat-resistant discoloration, moldability, and snap-fitting of parts are desired.

Special Publication No. 58-25379 Special Publication No. 58-35541

The present invention is suitable for molded parts having a thin-walled portion such as a hinge portion, has a UL94 thickness of 0.4 mm, has a flame retardancy of V-0 level, has no bleeding of a flame retardant, and has heat-resistant discoloration and moldability. , An object of the present invention is to provide a flame-retardant polyamide resin composition having excellent snap-fitting properties of parts.

The present inventors have completed the present invention as a result of diligent research in order to solve the above problems.

That is, the present invention has the following configuration.
[1] Polyamide resin (A) contains 97.5 to 94 parts by mass and melamine cyanurate (B) 2.5 to 6 parts by mass, and the polyamide resin (A) is a polyamide 66 resin (A-1). ) 50 to 80 parts by mass, 15 to 45 parts by mass of the polyamide 6 resin (A-2), and a phosphorus-based antioxidant () with respect to a total of 100 parts by mass of the components (A) and (B). C) is 0.01 to 1 part by mass, hindered phenol-based antioxidant (D) is 0.01 to 1 part by mass, and fatty acid metal salt-based lubricant (E) is 0.05 to 1 part by mass. A flame-retardant polyamide resin composition, which is characterized by being contained in.
[2] The flame-retardant polyamide resin composition according to [1], wherein the phosphorus-based antioxidant (C) is a compound having a pentaerythritol diphosphite skeleton.
[3] The flame-retardant polyamide resin composition according to [1] or [2], wherein the fatty acid metal salt-based lubricant (E) is a metal salt of an aliphatic carboxylic acid having 22 to 30 carbon atoms.
[4] A molded product having a hinge portion, which comprises the flame-retardant polyamide resin composition according to any one of [1] to [3].
[5] The molded product according to [4], wherein the molded product having the hinge portion is any one of a ferrite core cover, a binding band, and an electrical wiring protection member.

The flame-retardant polyamide resin composition of the present invention is excellent not only in heat-resistant discoloration and moldability, but also in snap-fitting because the molded product has appropriate elasticity and high breaking strength.

The present invention will be specifically described below.
[Polyamide resin (A)]
The polyamide resin (A) in the present invention is not particularly limited as long as it is a polymer having an amide bond (-NHCO-) in the main chain. The polyamide resin (A) is preferably crystalline, for example, polyamide 6 (PA6), polyamide 66 (PA66), polyamide 46 (PA46), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 610 (PA610). ), Polyamide 612 (PA612), Polymethaxylylene adipamide (PAMXD6), Hexamethylenediamine-terephthalic acid polymer (PA6T), Hexamethylenediamine-terephthalic acid and adipic acid polymer (PA6T / 66), Hexamethylenediamine. -Telephthalic acid and ε-caprolactam copolymer (PA6T / 6), trimethylhexamethylenediamine-terephthalic acid polymer (PATMD-T), metaxylylene diamine and adipic acid and isophthalic acid copolymer (PAMXD6 / MXDI), tri Examples of crystalline polyamide resins such as hexamethylenediamine and terephthalic acid and ε-caprolactam copolymer (PATMDT / 6), diaminodicyclohexylenemethane and isophthalic acid and lauryllactam copolymer, or blends thereof. However, it is not limited to these.

The blending amount (content) of the polyamide resin (A) is 97.5 to 94 parts by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. When the blending amount of the polyamide resin (A) is in this range, the composition can be provided with bleeding suppression of the flame retardant and retention of high flame retardancy. The blending amount (content) of the polyamide resin (A) is preferably 97 to 94.5 parts by mass, more preferably 97 to 95 parts by mass. In the flame-retardant polyamide resin composition of the present invention, the blending amount of each component is the content as it is.

The polyamide resin (A) in the present invention is preferably a mixture of a polyamide 66 resin (A-1) and a polyamide 6 resin (A-2) in terms of excellent moldability, melt fluidity, flame retardancy, and the like. Is.

Examples of the polyamide 66 resin (A-1) in the present invention include a polyamide 66 resin obtained by polycondensing adipic acid and hexamethylenediamine as raw materials. The relative viscosity of the polyamide 66 resin (A-1) is a value measured at a concentration of 1% in 98% sulfuric acid and a temperature of 25 ° C. according to JIS K6810, and is preferably 2.2 to 3.5. If the relative viscosity is less than 2.2, the mechanical properties tend to deteriorate, and if it exceeds 3.5, the melt fluidity tends to be insufficient. The relative viscosity of the polyamide 66 resin (A-1) is more preferably 2.3 to 3.0.

The terminal amino group concentration of the polyamide 66 resin (A-1) is not particularly limited, but is preferably 50 to 90 eq / ton, and more preferably 60 to 80 eq / ton in terms of heat-resistant discoloration.

The blending amount of the polyamide 66 resin (A-1) is preferably 50 to 80 parts by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. If the blending amount of the polyamide 66 resin (A-1) exceeds 80 parts by mass, the hinge property (snap fit property) is lowered, and if it is less than 50 parts by mass, the molding processability is likely to be lowered. The blending amount of the polyamide 66 resin (A-1) is more preferably 75 to 55 parts by mass from the viewpoint of the balance between snap fit and molding processability.

The polyamide 6 resin (A-2) in the present invention is a polyamide 6 resin obtained by polycondensation using ε-caprolactam as a raw material. The relative viscosity of the polyamide 6 resin (A-2) is a value measured at a concentration of 1% in 98% sulfuric acid and a temperature of 25 ° C. according to JIS K6810, and is preferably 2.0 to 4.5. If the relative viscosity is less than 2.0, the mechanical properties tend to deteriorate, and if it exceeds 4.5, the flame retardancy tends to be impaired. The relative viscosity of the polyamide 6 resin (A-2) is more preferably 2.2 to 3.5.

The terminal amino group concentration of the polyamide 6 resin (A-2) is not particularly limited, but is preferably 50 to 90 eq / ton, and more preferably 60 to 80 eq / ton in terms of heat-resistant discoloration.

The blending amount of the polyamide 6 resin (A-2) is preferably 15 to 45 parts by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. If the blending amount of the polyamide 6 resin (A-2) is less than 15 parts by mass, the hinge property (snap fit property) tends to decrease, and if it exceeds 45 parts by mass, the molding processability tends to decrease. The blending amount of the polyamide 6 resin (A-2) is more preferably 20 to 40 parts by mass from the viewpoint of the balance between snap fit and molding processability.

Amorphous polyamide resin (A-3) can also be blended to improve the appearance of the molded product.
Examples of the amorphous polyamide resin include 4,4'-diamino-3,3'-dimethyldicyclohexylmethane (CA), 4,4'-diaminodicyclohexylmethane (PACM), metaxylylenediamine (MXD), and trimethylhexamethylene. Diamines such as diamine (TMD), isophoronediamine (IA), 4,4'-diaminodicyclohexylpropane (PACP), hexamethylenediamine, and dicarboxylic acids such as terphthalic acid, isophthalic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid. Examples of polymers, copolymers, blends, etc. obtained by polycondensation from acids and lactams such as caprolactam and lauryllactam can be exemplified.

[Melamine cyanurate (B)]
As the melamine cyanurate (B) in the present invention, an equimolar reaction product of cyanuric acid and melamine is preferably mentioned. Further, a part of the amino group or the hydroxyl group in melamine cyanurate may be substituted with another substituent. Melamine cyanurate can be obtained, for example, by mixing an aqueous solution of cyanuric acid and an aqueous solution of melamine, reacting them under stirring at 90 to 100 ° C., and filtering the produced precipitate. The obtained solid can be used as it is, but it is preferable to pulverize and use it if necessary. The particle size is not particularly limited, but from the viewpoint of flame retardancy and toughness, the average particle size is preferably 0.5 to 20 μm, more preferably 1 to 15 μm.

The blending amount (content) of melamine cyanurate (B) is 2.5 to 6 parts by mass when the total of the polyamide resin (A) and melamine cyanurate (B) is 100 parts by mass. From the viewpoint of flame retardancy, it is 2.5 parts by mass or more, and from the viewpoint of toughness, it is 6 parts by mass or less. It is more preferably 3 to 5.5 parts by mass, and even more preferably 3 to 5 parts by mass. In the present invention, toughness is a property related to snap fit.

[Phosphorus-based antioxidant (C)]
The phosphorus-based antioxidant (C) in the present invention may be an inorganic compound or an organic compound, and is not particularly limited. Preferred phosphorus compounds include inorganic phosphates such as monosodium phosphate, disodium phosphate, trisodium phosphate, sodium phosphite, calcium phosphite, magnesium phosphite, manganese phosphite, and triphenylphos. Fight, trioctadecylphosphite, tridecylphosphite, triisodecylphosphite, trinonylphenylphosphite, diphenylisodecylphosphite, diphenylalkylphosphite, phenyldialkylphosphite, tris (nonylphenyl) phosphite, trilauryl Phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol di Phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, diisodecyloxypentaerythritol diphosphite, bis (2,4-di-tert-butyl-6-methylphenyl) ) Pentaerythritol diphosphite, bis (2,4,6-tris (tert-butylphenyl)) pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis (2,4-di-tert-butylphenyl) -4 , 4'-biphenylenediphosphonite, 6-isooctyloxy-2,4,8,10-tetra-tert-butyl-12H-dibenzo [d, g] -1,3,2-dioxaphosphocin, 6 -Fluoro-2,4,8,10-tetra-tert-butyl-12-methyl-dibenzo [d, g] -1,3,2-dioxaphosphocin, bis (2,4-di-tert-butyl) Examples thereof include -6-methylphenyl) methylphosphite and bis (2,4-di-tert-butyl-6-methylphenyl) ethylphosphite, which are blended to enhance heat-resistant discoloration.

As the phosphorus-based antioxidant (C), a phosphite compound is preferable. Among the phosphite compounds, a compound having a pentaerythritol diphosphite skeleton is preferable. Specifically, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite ("Adecastab PEP-36", molecular weight 633), bis (2,4-di-tert-butyl) Phenyl) pentaerythritol diphosphite (“Adecastab PEP-24G”, molecular weight 604), distearyl pentaerythritol diphosphite (“Adecastab PEP-8”, molecular weight 733), bis (nonylphenyl) pentaerythritol diphosphite (“Nonylphenyl) pentaerythritol diphosphite” Those having a pentaerythritol diphosphite skeleton such as "Adecastab PEP-4C", molecular weight 633) and having a molecular weight of about 600 to 800 can further improve the releasability without lowering the flame retardancy. Moreover, it is particularly preferable in that it is also suitable for snap fit.

The blending amount (content) of the phosphorus-based antioxidant (C) is 0.01 to 1 part by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. When the blending amount of the phosphorus-based antioxidant (C) is within this range, it is possible to suppress discoloration during extrusion processing and prevent secondary oxidative deterioration due to phosphorus-derived radicals. The blending amount of the phosphorus-based antioxidant (C) is preferably 0.1 to 0.5 parts by mass.

[Hindered phenolic antioxidant (D)]
Examples of the hindered phenolic antioxidant (D) in the present invention include N, N'-hexamethylene-bis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionamide and bis (3). , 3-Bis- (4'-hydroxy-3'-tert-butylphenyl) butanoic acid) glycol ester, 2,1'-thioethylbis (3- (3,5-di-tert-butyl-4-hydroxyphenyl)) Propionate, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenol), triethylene glycol-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate "SONGNOX2450", molecular weight 633) and the like, and a mixture of two or more of these can also be used.

The blending amount (content) of the hindered phenolic antioxidant (D) is 0.01 to 1 part by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. When the blending amount of the hindered phenolic antioxidant (D) is within this range, it is possible to prevent oxidative deterioration over time with an appropriate prescription amount according to the coordination bond of the polyamide composition. The blending amount of the hindered phenolic antioxidant (D) is preferably 0.1 to 0.5 parts by mass.

[Fatty acid metal salt lubricant (E)]
Examples of the fatty acid metal salt-based lubricant (E) in the present invention include metal salts of fatty acids having 12 to 40 carbon atoms such as stearic acid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid, and montanic acid. Be done. Of these, metal salts of aliphatic carboxylic acids having 22 to 30 carbon atoms are preferable, and alkali metals such as behenic acid, lignoceric acid, and montanic acid, or alkaline earth metal salts are more preferable in terms of releasability. Examples of the alkali metal or alkaline earth metal include lithium, sodium, magnesium, calcium salts and the like.

The blending amount (content) of the fatty acid metal salt-based lubricant (E) is 0.05 to 1 part by mass when the total of the polyamide resin (A) and the melamine cyanurate (B) is 100 parts by mass. If it is less than 0.05 parts by mass, the releasability may be lowered, and if it exceeds 1 part by mass, the flame retardancy may be lowered. The blending amount of the fatty acid metal salt-based lubricant (E) is preferably 0.1 to 0.8 parts by mass.

[Other ingredients]
The flame-retardant polyamide resin composition of the present invention may contain other flame-retardant polyamide resin compositions in addition to the above-mentioned (A), (B), (C), (D) and (E) as long as the object of the present invention is not impaired. Ingredients such as colorants such as pigments and dyes, additives such as heat stabilizers, weather resistance improvers, nucleating agents, plasticizers, mold release agents, antistatic agents, and other resin polymers can be added. .. The flame-retardant polyamide resin composition of the present invention preferably occupies 80% by mass or more in total of the above-mentioned components (A), (B), (C), (D), and (E). It is more preferable to occupy 90% by mass or more, and further preferably to occupy 95% by mass or more.

A suitable molded part obtained by using the flame-retardant polyamide resin composition of the present invention is a molded product having a hinge portion, and specifically, a connector used in the fields of electrical / electronic parts, automobile parts, and the like. Molded parts with thin hinges such as coil bobbins, breakers, electromagnetic switches, holders, plugs, sockets, switches, cases, covers, etc. More specifically, ferrite core covers, binding bands, electrical wiring protection members, etc. , Heat-resistant discoloration and snap-fitting are required parts.

The method for producing the flame-retardant polyamide resin composition of the present invention is not particularly limited, and a general single-screw extruder, twin-screw extruder, pressure kneader, or the like can be used as the kneading device. A twin-screw extruder is particularly preferred. In one embodiment, the above (A), (B), (C), (D), (E) and, depending on the application, pigments and the like are mixed and charged into a twin-screw extruder. By uniformly kneading with a twin-screw extruder, a polyamide-based resin composition having excellent toughness and flame retardancy can be produced. The kneading temperature of the twin-screw extruder is preferably 220 to 300 ° C., and the kneading time is preferably about 2 to 15 minutes.

The present invention will be described in more detail below with reference to Examples, but the present invention is not limited to these Examples.

The following components were used.
Polyamide resin (A);
A1: Polyamide 66 (RV = 2.8) Vydyne 21FSR (manufactured by Ascend), melting point 265 ° C.
A2: Polyamide 6 (RV = 2.6) ZISAMIDE TP4208 (manufactured by Shuseisha), melting point 225 ° C.

Melamine cyanurate (B);
B: MC6000 (manufactured by Nissan Chemical Industries, Ltd.)

Phosphorus-based antioxidant (C);
C1: ADEKA STAB PEP-36 (manufactured by ADEKA Corporation)
C2: ADEKA STAB 3010 (Triisodecylphosfite) (manufactured by ADEKA Corporation)

Hindered phenolic antioxidant (D);
D: SONGNOX2450 (manufactured by Songwon International Japan)

Fatty acid metal salt lubricant (E);
E1: Calcium montanate CS-8-CP (manufactured by Nitto Kasei Kogyo Co., Ltd.)
Other mold release agents;
E2: Aliphatic ester Recolve WE-40 (manufactured by Clariant Japan Co., Ltd.)

[Examples 1 to 6, Comparative Examples 1 to 4]
In the production of the evaluation sample, each raw material was weighed in the blending ratio of the polyamide resin composition shown in Table 1, mixed with a tumbler, and then put into a twin-screw extruder. The set temperature of the twin-screw extruder was 250 ° C. to 300 ° C., and the kneading time was 5 to 10 minutes. The obtained pellets were molded with various evaluation samples using an injection molding machine. The cylinder temperature of the injection molding machine was 250 ° C. to 290 ° C., and the mold temperature was 80 ° C.

Various evaluation methods are as follows. The evaluation results are shown in Table 1.
1. 1. Relative viscosity of polyamide resin [RV] (98% sulfuric acid solution method)
The measurement was carried out using a Ubbelohde viscous tube at 25 ° C. in a 98 mass% sulfuric acid solution at a polyamide resin concentration of 1 g / dl.
2. 2. Melting point of polyamide resin Using a differential scanning calorimeter, Seiko Instruments Co., Ltd. EXSTAR 6000, the temperature was measured at a heating rate of 20 ° C./min, and the endothermic peak temperature was determined.
3. 3. Snap fit (tensile strength, tensile elongation): Measured according to ISO527.
4. Combustibility: Measured according to UL94, vertical combustion test. V-0 represents the highest flame retardancy.
5. Bleedability: A molded product of 100 mm × 100 mm with a thickness of 2 mm was allowed to stand at a constant temperature and humidity chamber set at a temperature of 80 ° C. and 95% RH for 96 hours at least twice, and then returned to room temperature to have precipitates on the surface. It was visually confirmed with a stereomicroscope.
6. Thermal discoloration: The color difference (ΔE) between the pellets after the temperature was 120 ° C. and the time left in the oven for 8 hours and the pellets before treatment was calculated.
7. Moldability: Molding was performed under the above molding temperature conditions using a mold equipped with a mold release force measuring device, and the mold release force from the 31st shot to the 35th shot was measured to obtain the mold release resistance value.

In Examples 1 to 6, the tensile elongation is 20% or more, and the toughness inherent in the polyamide resin (A) is maintained. In addition, since the tensile strength is not significantly impaired, it is expected that good snap fit can be obtained. Even in terms of flame retardancy at a thickness of 0.4 mm, Examples 1 to 6 have achieved a V-0 evaluation. In terms of thermal discoloration, Examples 1 to 6 have a ΔE of 20 or less after 8 hours at 120 ° C., indicating that discoloration in a thermal environment is suppressed. In terms of moldability, the resistance value of the molded product at the time of mold release is 1 MPa or less, and the composition is extremely unlikely to be deformed or adhered during mold release even after continuous molding. .. Further, comparing Examples 1 to 5 using a phosphorus-based antioxidant having a pentaerythritol diphosphite skeleton with Example 6 using a phosphorus-based antioxidant having no pentaerythritol diphosphite skeleton, the former has snap-fitting property and thermal discoloration. It can be seen that the property and moldability (mold release property) are more excellent.

On the other hand, although Comparative Examples 1 to 4 partially satisfy the characteristics, Comparative Example 1 has a resistance value of 5 MPa at the time of mold release of the molded product, and the molded product can remain without being released during continuous molding. It is not preferable because it has sex. In Comparative Example 2, ΔE after 8 hours at 120 ° C. is 26, and the discoloration when placed in a thermal environment is large, which is not preferable as an external component. In Comparative Example 3, the flame retardancy at a thickness of 0.4 mm was evaluated as V-2, and it cannot be said that the flame retardancy is sufficiently maintained. Finally, Comparative Example 4 has a tensile elongation of 17%, which is not preferable because brittle fracture due to insufficient snap-fitting property cannot be suppressed.

The flame-retardant polyamide resin composition of the present invention is suitable for a molded product having a hinge portion, and the obtained molded product is excellent in snap-fitting property, so that it is desired to have excellent snap-fitting property. It can be suitably used for automobile parts and the like.

Claims

It is contained in a proportion of 97.5 to 94 parts by mass of the polyamide resin (A) and 2.5 to 6 parts by mass of the melamine cyanurate (B), and the polyamide resin (A) is the polyamide 66 resin (A-1) 50 to 50 to The phosphorus-based antioxidant (C) is added to 80 parts by mass, 15 to 45 parts by mass of the polyamide 6 resin (A-2), and 100 parts by mass in total of the components (A) and (B). It contains 0.01 to 1 part by mass, 0.01 to 1 part by mass of hindered phenol-based antioxidant (D), and 0.05 to 1 part by mass of fatty acid metal salt-based lubricant (E). A flame-retardant polyamide resin composition.
The flame-retardant polyamide resin composition according to claim 1, wherein the phosphorus-based antioxidant (C) is a compound having a pentaerythritol diphosphite skeleton.
The flame-retardant polyamide resin composition according to claim 1 or 2, wherein the fatty acid metal salt-based lubricant (E) is a metal salt of an aliphatic carboxylic acid having 22 to 30 carbon atoms.
A molded product having a hinge portion, which comprises the flame-retardant polyamide resin composition according to any one of claims 1 to 3.
The molded product according to claim 4, wherein the molded product having the hinge portion is any one of a ferrite core cover, a binding band, and an electrical wiring protection member.