JP2009108221A - Polyamide resin composition for casing of electrical/electronic equipment and casing of electrical/electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamide resin composition that has high stiffness, thin-wall moldability, radio communication capability and flame retardancy at the same time for use in a specific casing of electrical/electronic equipment produced by integrating a structure comprising a radio wave shielding material with a structure comprising the polyamide resin composition, i.e., a casing of electrical/electronic equipment having both an electromagnetic wave shielding property and radio communication capability. <P>SOLUTION: The polyamide resin composition for a casing of electrical/electronic equipment contains (A) 15-60 wt.% polyamide resin comprising (A1) a terpolymer and (A2) a polyamide resin other than the terpolymer (A1), (B) 35-65 wt.% glass fiber, (C) 3-10 wt.% red phosphorus and (D) 2-10 wt.% magnesium hydroxide, based on 100 wt.% polyamide resin composition wherein the terpolymer (A1) is a terpolymer consisting of (A1a) a hexamethylene adipamide unit, (A1b) a hexamethylene isophthalamide unit and (A1c) a caproamide unit. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyamide resin composition for use in an electric / electronic equipment casing obtained by integrating two types of structures, a structure made of a radio wave shielding material (I) and a structure made of a polyamide resin composition (II). (Hereinafter, it may be referred to as “polyamide resin composition for electrical and electronic equipment casing” or simply “polyamide resin composition”.) (II).

  In recent years, as electric and electronic devices have become more portable, higher performance molded products have been demanded. In addition to the radio wave shielding required to prevent malfunctions, parts that make up equipment are required to be thin while achieving high strength and rigidity to reduce weight. . Furthermore, at present, products with built-in wireless communication functions are rapidly expanding, and there is a demand for a molded product having radio communication performance while having radio wave shielding properties.

  Patent Document 1 discloses a radio wave shielding molded product in which a structure made of a resin composition reinforced with a large number of continuous conductive fibers and a structure made of a thermoplastic resin composition are integrated. Yes. According to this method, radio wave shielding, high strength / high rigidity, and thinning can be achieved.

  However, when the disclosed thermoplastic resin containing a carbon fiber is used, the wireless communication performance deteriorates, so that it is impossible to wirelessly transmit and receive information that has recently been increased in capacity. is there. In addition, it does not mention the flame retardancy required as an electric / electronic device molded article, and there is no description of the thin-wall moldability important in manufacturing, and the above-mentioned high-performance molded article that has been required in recent years can be obtained. Absent.

  Polyamide resins, on the other hand, have been used in a wide range of fields such as automotive and electrical / electronic equipment applications due to their excellent moldability, mechanical properties, chemical resistance, and abrasion resistance. With the progress of molding technology, parts that require higher appearance have been actively put into practical use.

  Patent Document 2 discloses a resin composition comprising a copolymerized polyamide resin comprising a hexamethylene adipamide unit, a hexamethylene isophthalamide unit and a caproamide unit, a fiber reinforcing material and an inorganic filler. Certainly, since the resin composition is excellent in rigidity and fluidity, it can be used for molded articles in the automotive field, the electric and electronic field, and the like.

  However, although there is a general description in the document that a flame retardant can be added, a specific method for imparting flame retardancy is not specified, and the high flame retardancy required particularly for molded articles of electrical and electronic equipment from this document. Sex cannot be achieved. In addition, although there is a description of an electrical / electronic device casing in its application, there is no description regarding use in an integrated manner with another member, for example, a radio wave shielding material.

As described above, a specific electrical and electronic equipment casing in which a structure made of a radio wave shielding material and a structure made of a polyamide resin composition are integrated, that is, has an electromagnetic wave shielding property and also has wireless communication performance. There has been a demand for a polyamide resin composition that has high rigidity, thin-wall formability, wireless communication performance, and flame retardancy, which is used for electrical and electronic equipment casings.
International Publication No. 2004/060658 Pamphlet JP 2006-56938 A

  An object of the present invention is to be used for an electrical and electronic equipment casing in which a structure made of a radio wave shielding material (I) and a structure made of a polyamide resin composition (II) having both radio wave shielding properties and wireless communication performance are integrated. Another object of the present invention is to provide a polyamide resin composition (II). Specifically, it is to provide a polyamide resin composition having high rigidity, thin-wall formability, wireless communication performance, and flame retardancy.

As a result of intensive studies to solve the above problems, the present inventors have found that this can be achieved by blending an appropriate amount of a polyamide resin containing a specific polyamide resin, glass fiber, red phosphorus, and magnesium hydroxide. That is, the above problem is
A polyamide resin composition (II) used in an electrical and electronic equipment casing in which two types of structures, a structure made of a radio wave shielding material (I) and a structure made of a polyamide resin composition (II), are integrated. The polyamide resin composition contains (A) (A1) terpolymer and a polyamide resin other than (A2) (A1) with respect to 100% by weight of the polyamide resin composition. Polyamide resin 15 to 60% by weight, (B) glass fiber 35 to 65% by weight, (C) red phosphorus 3 to 10% by weight, (D) magnesium hydroxide 2 to 10% by weight, The terpolymer is a terpolymer comprising (A1a) a hexamethylene adipamide unit, (A1b) a hexamethyleneisophthalamide unit, and (A1c) a caproamide unit. Apparatus housing for the polyamide resin composition.
The solution is achieved.

  According to the present invention, it is possible to obtain an electric and electronic equipment casing having both a radio wave shielding property and a wireless communication performance by integrating a structure made of a radio wave shield material and a structure made of a polyamide resin composition.

  The present invention will be specifically described below.

  The (A) polyamide resin constituting the present invention comprises (A1) a terpolymer polyamide (PA66 / 6I / 6) resin and (A2) a polyamide resin other than (A1) described below. It is essential.

  The polyamide resin of (A1) terpolymer comprises (A1a) hexamethylene adipamide (PA66) units, (A1b) hexamethyleneisophthalamide (6I) units, and (A1c) caproamide (PA6) units. It is essential. Here, the polyamide resin of (A1) terpolymer is (A1a) 70 to 85% by weight of PA66 units, (A1b) 5 to 29% by weight of PA6I units, and (A1c) 1 to 10% by weight of PA6 units. The weight ratio of (A1b) PA6I unit to (A1c) PA6 unit is preferably (PA6I / PA6) of 1.0 or more. If the PA66 unit is less than 70% by weight, the excellent mechanical properties and heat resistance inherent in the polyamide resin may be unsatisfactory. If the PA66 unit exceeds 85% by weight, the molded product surface property, low sinkability, etc. may not be satisfied. There is a case.

  Furthermore, it is preferable that the relative viscosity of the (A1) ternary copolymer polyamide resin is 1.8 to 2.8 [-] (98% sulfuric acid method). If it is less than 1.8, the durability may not be satisfactory, and if it exceeds 2.8, the fluidity during molding may not be satisfactory. More preferably, the one in the range of 2.0 to 2.5 is used.

  (A2) Polyamide resins other than the polyamide resin of the (A1) terpolymer are not particularly limited, and are PA6 resin, PA66 resin, or PA6 / 66 resin, XD6 nylon because of their availability. Resins, MXD6 nylon resin, PA6T / 6I resin, PA66 / 6I resin, and mixtures thereof are preferably used. More preferably, PA6 resin, PA66 resin, MXD6 nylon resin, and most preferably PA6 resin is used.

  (A) The blending ratio of the polyamide resin other than the (A1) terpolymer polyamide resin and the (A2) (A1) terpolymer polyamide resin in the polyamide resin is (A1) 5 to 95 weights. % And (A2) between 95 and 5% by weight. When the polyamide resin of the (A1) terpolymer is less than 5% by weight, the flame retardancy and fluidity may be reduced. On the other hand, other than the polyamide resin of the (A2) (A1) terpolymer When the polyamide resin is less than 5% by weight, flame retardancy may be lowered.

  (B) glass fiber which comprises this invention can be used if it is generally used for a glass fiber reinforced resin composition. Among them, the thickness (diameter) of the glass fiber is preferably 9 to 25 μm, more preferably 10 to 15 μm per one. If it exceeds 25 μm, the tensile strength may decrease. Moreover, the kind of glass fiber may be any of alkali-free glass, low alkali glass, and alkali-containing glass, and those having various compositions conventionally used as glass fibers can be used.

  (C) Red phosphorus constituting the present invention preferably has an average particle size of 0.01 to 35 μm before blending with the resin composition from the viewpoint of flame retardancy and mechanical properties. The thing of 30 micrometers is preferable. In addition, red phosphorus is unstable as it is, and since it has the property of gradually dissolving in water or reacting with water, it is preferable to apply a treatment to prevent this, especially by pulverizing red phosphorus. In addition, red phosphorus is finely divided without forming a crushing surface highly reactive with water and oxygen on the surface of red phosphorus, and a small amount of aluminum hydroxide or magnesium hydroxide is added to red phosphorus to catalyze the oxidation of red phosphorus. In particular, red phosphorus coated with a phenolic thermosetting resin or an epoxy thermosetting resin is preferable.

  (D) Magnesium hydroxide constituting the present invention can be used as a natural type or a synthetic type, but a synthetic type having a small average particle size distribution range and (A) excellent dispersibility in a polyamide resin is preferred. In addition, the average crystal grain size is preferably 0.2 to 50 μm, more preferably 0.5 to 10 μm from the viewpoint of flame retardancy and mechanical properties. Further, the surface treatment may be performed with a known surface treatment agent or may be untreated, but when the resin composition of the present invention is molded, the surface is treated with (A) a surface treatment agent that does not cause a chemical reaction with the polyamide resin. It is preferable that the treatment is performed.

  The polyamide resin composition according to the present invention includes (A) 15 to 55% by weight of the polyamide resin, (B) 40 to 65% by weight of glass fiber, (C) 3 to 10% by weight of red phosphorus, and (D) hydroxylation. By constituting in the range of 2 to 10% by weight of magnesium, the desired rigidity, fluidity, flame retardancy, and radio wave transmission can be obtained. It is not possible to obtain a polyamide resin composition having

  As for the polyamide resin composition concerning this invention, it is more preferable that the combustibility in UL94 specification is V-0 at 1 mm thickness. Some molded products in the electric and electronic field are required to be flame retardant. In particular, a housing of a device including a device that can generate heat such as a personal computer, a digital video camera, and a liquid crystal projector is V-0 in the UL94 standard. It is preferable. Here, the UL94 standard is a standard for flammability testing of plastics materials established by the Underwriters Laboratory, which is widely used as a global standard and is not legally binding in Japan. It is generally used as a judgment of availability.

  From the viewpoint of wireless communication performance, the polyamide resin composition according to the present invention or the structure comprising the polyamide resin composition (II) preferably has a radio wave shielding property at a frequency of 1 GHz measured by the KEC method of 10 dB or less. More preferable is 5 dB or less. Here, the KEC method is a measurement method defined by the Kansai Electronics Industry Promotion Center, which measures the attenuation of radio waves with a spectrum analyzer by inserting a test piece into a shield box divided vertically or horizontally. is there.

  The structure of the radio wave shielding material (I) integrated with the structure made of the polyamide resin composition (II) according to the present invention has a frequency of 1 GHz measured by the KEC method from the viewpoint of preventing malfunction due to external radio waves. The electromagnetic wave shielding property at is 40 dB or more. The radio wave shielding value is preferably 45 dB or more, and more preferably 50 dB or more.

  The structure made of the radio wave shielding material (I) is not particularly limited as long as it has radio wave shielding properties, but is reinforced with metals such as magnesium alloy and aluminum alloy, and conductive fibers from the viewpoint of formability and mechanical properties. A structure comprising a thermosetting resin composition or a thermoplastic resin composition is preferred. As the conductive fibers, for example, metal fibers such as aluminum, brass, and stainless steel, polyacrylonitrile-based, rayon-based, lignin-based, pitch-based carbon fibers, and graphite fibers can be used. Examples of the thermosetting resin include unsaturated polyesters, vinyl esters, epoxies, phenols (resol type), urea melamines, polyimides, copolymers thereof, modified products, or resins obtained by blending two or more types. Among them, those containing at least an epoxy resin are preferable. As the thermoplastic resin, for example, a polyamide resin, a polyester resin, a polyphenylene sulfide resin, a polycarbonate resin or the like alone or an alloy with another resin is preferably used. Among the above descriptions, those composed of a thermosetting resin composition reinforced with continuous carbon fibers are most preferable from the viewpoints of rigidity and lightness.

  The method of integrating the structure composed of the polyamide resin composition (II) and the structure composed of the radio wave shielding material (I) according to the present invention includes fitting, bonding with an adhesive, thermal welding, vibration welding, ultrasonic welding. , Laser welding, insert injection molding, and outsert injection molding.

  The best mode of the electrical and electronic equipment housing in which the structure made of the polyamide resin composition (II) according to the present invention and the structure made of the radio wave shielding material (I) are integrated is the viewpoint of mechanical strength and lightness. Thus, the structure made of the polyamide resin composition of the present invention and the structure made of a thermosetting resin reinforced with continuous carbon fibers are bonded via a thermoplastic resin adhesive layer.

  Here, as the thermoplastic resin constituting the thermoplastic resin adhesive layer, a polyamide resin is preferable. The best manufacturing method is the method described in International Publication No. 2004/060658 pamphlet. That is, a laminate comprising a thermosetting resin reinforced with continuous carbon fibers and a film made of a polyamide resin formed on the surface of the thermosetting resin, and a structure comprising the polyamide resin composition of the present invention, This is a method in which the polyamide resin of the present invention is outsert injection-molded after ultrasonic welding or the laminate is inserted into a mold and integrated through the polyamide resin of the film.

  Examples of the use of the electrical and electronic equipment housing in which the structure made of the polyamide resin composition (II) according to the present invention and the structure made of the radio wave shielding material (I) are integrated include a display, a parabolic antenna, and a personal computer. It is useful for electrical and electronic equipment cases such as notebook computers, mobile phones, digital still cameras, digital video cameras, PDAs, portable MDs, and home electronic game machines. Among them, it is useful for electronic electrical equipment cases such as notebook personal computers, mobile phones, and PDAs that have high rigidity and light weight, have complicated shapes, and require radio wave shielding and wireless communication performance.

  Hereinafter, although an example is given and the present invention is explained in detail, the gist of the present invention is not limited only to the following examples.

[raw materials]
The raw materials used in the examples and comparative examples are as shown below. The polyamide used was polymerized according to a conventional method.

Polyamide resin 1: PA66 / 6I / 6 = 80 wt% / 15 wt% / 5 wt% (relative viscosity 2.1)
Polyamide resin 2: PA6 (relative viscosity 2.6)
Glass fiber: diameter 13 μm, surface-treated for polyamide, 3 mm long chopped strand Carbon fiber: carbon fiber T300 manufactured by Toray Industries, Inc. 3 mm long chopped strand Red phosphorus: phosphorus chemical industry ) Nova Excel 140 (average particle size about 30μm)
Magnesium hydroxide: Kisuma 5E (average particle size: about 1.0 μm) manufactured by Kyowa Chemical Industry Co., Ltd.

[Material Evaluation Method]
Each material was subjected to Nippon Steel Works J350EII-SP type injection molding machine, cylinder temperature: 260 ° C, mold: 80 ° C, injection time: 10 seconds, cooling: 20 seconds, injection speed: 70%, injection pressure: filling lower limit Various test pieces were prepared under the setting condition of pressure +1.0 MPa and measured by the following method.

  (1) Flexural modulus: measured in accordance with ASTM D790. The higher this value, the better the rigidity.

  (2) Fluidity: A square plate mold (fan gate) having a size of 200 mm × 200 mm × 1.0 mm was used, and evaluation was performed with a lower limit of filling pressure. Filling is the first condition, but the lower the injection pressure, the better the fluidity, the wider the range of molding conditions and the thinner the molded product.

  (3) Flammability: 1 mm thickness was evaluated according to UL94V standard. The flame retardancy is excellent in the order of V-0> V-1> V-2 (approximately equal to V-out).

  (4) Radio wave permeability: 1 mm-thick radio wave shielding property was measured according to the KEC method. The lower this value, the better the radio wave transmission.

[Example 1]
Polyamide resin in the ratio shown in Table 1 (the polyamide resin was a blended product having a ratio of PA66 / 6I / 6 resin 40 wt% and PA6 resin 60 wt% to 100 wt% polyamide resin) It is fed from the main feeder of TEX-30 twin screw extruder manufactured by Steel Works, and melt kneaded at a kneading temperature of 290 ° C and a screw rotation speed of 200 rpm by supplying glass fiber, red phosphorus and magnesium hydroxide from the side feeder in the middle of the cylinder. Went. After the obtained pellets were dried, the flexural modulus, fluidity, combustibility, and radio wave permeability were evaluated according to the material evaluation method. As a result, as shown in Table 1, all items had excellent characteristics.

[Comparative Example 1]
Pelletization and material evaluation were performed in the same manner as in the method described in Example 1, except that carbon fiber was blended instead of glass fiber. As a result, as shown in Table 1, the radio wave shielding property was high and the wireless communication performance was inferior.

[Examples 2 to 4, Comparative Examples 2 to 7]
In the same manner as in the method described in Example 1, pelletization and material evaluation were performed at the blending ratio shown in Table 1. As a result, as shown in Table 1, in the specific compounding ratio shown in the present invention, excellent characteristics were exhibited in all items of flexural modulus, fluidity, flame retardancy, and radio wave permeability.

[Comparative Examples 8 and 9]
Pelletization and material evaluation were performed in the same manner as in the method described in Example 1 except that PA66 / 6I / 6 resin alone or PA6 resin alone was used as the polyamide resin. As a result, as shown in Table 2, the intended characteristics were not obtained.

[Example 5]
As a radio wave shielding material, carbon fiber prepreg P60553-12 manufactured by Toray Industries, Inc. was cut into a predetermined size to produce a flat molded body. First, six prepregs are laminated on a female mold so that the longitudinal direction of the rectangular bottom is 0 ° and the fiber direction is 45 °, −45 °, 90 °, 90 °, −45 °, 45 ° from the top. did. From the top of the last laminated prepreg, as a thermoplastic resin composition layer, Toray Industries, Ltd., terpolymer polyamide resin CM4000 (nylon 6/66/610, melting point 150 ° C., basis weight 30 g / m ² , single fiber fineness Two non-woven fabrics of 0.2 tex) cut to the same size as the molded body were stacked and laminated. Next, a male mold was set and press molding was performed. The thermoplastic resin composition layer was melted by preheating at 160 ° C. for 5 minutes in a press molding machine, and then cured by heating at 150 ° C. for 30 minutes while applying a pressure of 6 MPa. After the curing was completed, it was cooled at room temperature and demolded to obtain a radio wave shielding material having an average thickness of 0.8 mm. The electric field shielding property of the obtained radio wave shielding material in the KEC method was 70 dB in the 1 GHz band.

  Next, the radio wave shielding material is inserted into an injection mold, and the polyamide resin composition of Example 1 is injection molded as a radio wave transmitting material on the surface of the radio wave shielding material having the thermoplastic resin composition layer. Were molded and integrated to obtain an electronic device casing. The average thickness of the radio wave transmitting material was 1.0 mm, and the electric field shielding property in the KEC method was 0 dB in the 1 GHz band. Moreover, this housing was lightweight and highly rigid because of the feel of the hand.

Claims (4)

A polyamide resin composition (II) used in an electrical and electronic equipment casing in which two types of structures, a structure made of a radio wave shielding material (I) and a structure made of a polyamide resin composition (II), are integrated. The polyamide resin composition contains (A) (A1) terpolymer and a polyamide resin other than (A2) (A1) with respect to 100% by weight of the polyamide resin composition. Polyamide resin 15 to 60% by weight, (B) glass fiber 35 to 65% by weight, (C) red phosphorus 3 to 10% by weight, (D) magnesium hydroxide 2 to 10% by weight, The terpolymer is a terpolymer comprising (A1a) hexamethylene adipamide units, (A1b) hexamethyleneisophthalamide units, and (A1c) caproamide units. Apparatus housing for the polyamide resin composition. The polyamide resin composition for electrical and electronic equipment housings according to claim 1, wherein the combustibility in UL94 standard is V-0 at a thickness of 1 mm. (A2) The polyamide resin composition for electrical and electronic equipment casings according to claim 1 or 2, wherein the polyamide resin other than (A1) is a polyamide 6 resin. An electrical and electronic equipment housing in which two types of structures, a structure made of the radio wave shielding material (I) and a structure made of the polyamide resin composition according to any one of claims 1 to 3, are integrated.