JP2949675B2 - Conductive resin composition for injection molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin composition for injection molding which is effective for forming trays, containers and other transport containers used in an IC manufacturing process, or racks used in a board mounting line. .

[0002]

2. Description of the Related Art Conventionally, as a material for forming containers such as trays and containers used for transportation in an IC manufacturing process, or racks used in a board mounting line, conductive materials based on polystyrene or polypropylene are mainly used. Sex compounds have been put to practical use. However, in recent years, in the IC mounting process, the line environment has been increasing in density and speed, and moreover, the IC itself is often exposed to high heat. Such a change in the environment may cause inconvenient phenomena such as cracking of the material due to moisture contained in the sealing material. Therefore, I
Containers and racks used in the C manufacturing process and the substrate mounting line are required to have higher heat resistance. It is also necessary to increase dimensional accuracy in order to respond to automation and robotization of the process.

On the other hand, polystyrene, which has been widely used as a conventional compound resin, has few problems in terms of dimensional accuracy, but does not satisfy the above-mentioned required characteristics because the heat deformation temperature is limited to about 80 ° C. at the actual use temperature. There are drawbacks. As a composition for solving this drawback, a composition in which mica or talc is blended with polypropylene in place of polystyrene has also been proposed (JP-A-58-206646 and JP-A-58-108242). However, this component composition reaches a practical level in terms of heat resistance, but shrinks in dimensional change due to heat history, and has poor dimensional stability. In a polypropylene-based conductive resin material reinforced with this kind of inorganic filler, even after being subjected to an annealing treatment for stabilizing shrinkage after molding, the shrinkage does not stop due to repeated heat history, even if it is put to practical use. There is a problem that the dimensional tolerance is deviated with time, and the material is liable to be deformed such as warp or twist with the progress of shrinkage.

[0004]

SUMMARY OF THE INVENTION The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a polypropylene-based component composition reinforced with mica as an inorganic filler has been used. It has been confirmed that when a specific organic nucleating material is added, the heat deformation temperature after molding is improved, the dimensional stability is rapidly advanced, and the dimensional change due to repeated heating is extremely small.

The present invention has been developed on the basis of the above findings, and its object is to provide a method for drying, reliability tests, post-soldering processes, etc., when exposed to an actual use temperature environment of about 120 to 150 ° C. Another object of the present invention is to provide a conductive resin composition for injection molding suitable for molding heat-resistant IC trays, racks, containers, and the like, in which dimensional changes due to heat history are extremely small.

[0006]

In order to achieve the above object, the conductive resin composition for injection molding according to the present invention comprises 40 to 70% by weight of a polypropylene resin, 20 to 50% by weight of mica, and an average particle diameter of 100 μm. Below 50ml oil absorption
/ 100 g or more of carbon black of 5 to 30% by weight and an organic nucleating agent of 0.1 to 3% by weight, and a heat distortion temperature (ASTM D-684: 4.6 k)
gf / cm ² ) is 140 ° C. or higher and volume resistivity (SRI)
The configuration is characterized in that S2301) has a characteristic of 1 × 10 ⁶ Ωcm or less.

As the polypropylene resin as the composition base of the present invention, a homopolymer or a block polymer is used from the viewpoint of heat resistance and moldability, and it is particularly preferable to select one or more having a MFR of 1 or more. . It is necessary to use mica for the inorganic filler as a reinforcing material in order to obtain a heat deformation temperature of 140 ° C. or higher, and it is also possible to use it together with talc. Mica has an average particle size of 100 μm to improve appearance, abrasion peeling, and weld properties.
It is preferable to use the following fine particles. Furnace black and acetylene black can be used alone or in combination as the carbon black serving as the conductivity-imparting material. However, from the viewpoint of the conductivity-imparting ability, characteristics of an average particle diameter of 100 μm or less and an oil absorption of 50 ml / 100 g or more are required. Those provided are preferably used.

The preferred compounding ratio of these main components is 40 to 70% by weight of a polypropylene resin, 20 to 50% by weight of mica, and 5 to 30% by weight of carbon black. I do. Particularly, the lower limit of the compounding ratio is important. If the polypropylene resin is less than 40% by weight, the moldability deteriorates, and if the mica is less than 20% by weight, 140 ° C. (ASTM D-648: 4.6 kgf / cm)
² ) It is difficult to secure the heat deformation temperature above, and if the carbon black is less than 5% by weight, the volume resistivity (SRIS2301) cannot be shifted to 1 × 10 ⁶ Ωcm or less.

The organic nucleating agent blended in the main component is a component that contributes to dimensional stability, and includes aluminum hydroxy-di (tert-butylbenzoate) and 2,2'-methylenebis (4,6-di-tert-phosphate). -Butylphenyl) sodium or lower alkyl-substituted dibenzylidene sorbitol is optionally used. The amount of the organic nucleating agent added is 0.1
The effect of dimensional stabilization is exhibited from the weight%, but the effect is saturated at a certain amount. Therefore, it is set in the range of 0.1 to 3% by weight, preferably 0.1 to 1% by weight.

After adding an antioxidant, a stabilizer, a dispersant, a coupling agent and the like to the above-mentioned component composition, if necessary, using a device such as a Banbury mixer, a twin-screw extruder, and a pressure kneader. The mixture is kneaded to obtain the conductive resin composition for injection molding of the present invention.

[0011]

According to the present invention, a composition comprising a main component of polypropylene resin, mica and carbon black having an average particle diameter of 100 μm or less and an oil absorption of 50 ml / 100 g or more functions to prevent thermal deformation and impart conductivity. In addition, the dimensional change of the material is effectively improved by the action of blending the organic nucleating agent.

[0012] Such an action is synergistic, and the heat distortion temperature (ASTM D-648: 4.6 kgf / cm ² ) 14
0 ° C or higher, volume resistivity (SRIS2301) 1 × 1
0 ⁶ [Omega] cm or less and unique advantageous effect that the dimensional change due to dimensional stabilization is rapidly repeated thermal history during annealing after molding is very low is applied.

[0013]

Hereinafter, examples of the present invention will be described in comparison with comparative examples.

Examples 1 to 9 and Comparative Examples 1 to 4 Components having the compositions shown in Table 1 were uniformly melt-kneaded using a 1.71 volume Banbury mixer. The kneaded material was formed into a sheet by a mixing roll and granulated into a square pellet by a square pelletizer. Then, the square pellet was formed into a rod shape (205 mm × 12.8 mm × 6.4 mm) by an injection molding machine, and left in a room at 22 ± 2 ° C. for 24 hours to obtain an evaluation sample.

[0015]

[Table 1]

In the components shown in Table 1, H of the polypropylene (PP) resin is a homopolymer of MFR8 [Mitsui Noblen JHHG manufactured by Mitsui Toatsu Chemicals, Inc.], and B is a block polymer of MFR8 [Mitsui Pressure Chemical Co., Ltd.
Mitsui Noblen BJHHG]. Among the inorganic fillers, M is mica [Preco Squid S-32, manufactured by Pleco.
5], T is talc [manufactured by Muramatsu Sangyo Co., Ltd., high filler talc 16]. Of carbon black (CB),
F is furnace black [average particle diameter 31 mμ, oil absorption 360 ml / 100 g; Ketchen Black EC manufactured by Lion Corporation], A is acetylene black [average particle diameter 41 mμ, oil absorption 212 ml / 100 g; Denki Kagaku Kogyo Co., Ltd.] Manufactured by Denka Black Co., Ltd.). Among organic nucleating agents, H is aluminum hydroxydi (tert-butylbenzoate) [manufactured by Shell Chemical Co., Ltd.], and R is phosphoric acid 2,2.
2'-methylenebis (4,6-di-tert-butylphenyl) sodium [Mark NA-, manufactured by Asahi Denka Co., Ltd.
11], M is methyl-substituted dibenzylidene sorbitol [Gelol MD, manufactured by Shin Nippon Rika Co., Ltd.]. The antioxidant is Irganox 10 manufactured by Ciba-Geigy.
It is 10.

Next, various characteristics of each evaluation sample were measured, and the results are shown in Table 2. The measurement conditions of the characteristics were as follows. (1) MFR: 230 ° C., 5 kgf. (2) Heat deformation temperature: ASTM D-648 (4.6 kgf / cm ² )
According to (3) Surface resistance: The probe electrode resistance (Loresta CPA type, manufactured by Mitsubishi Yuka Co., Ltd.) on the surface before heating was measured. (4) Volume resistivity: Measured in accordance with SRIS 2301 on a test piece punched from a 2 mm thick injection molded plate. (5) Heat shrinkage (%): The shrinkage at one time is (molding size)-
Calculate with the formula of (Dimension after heating) / (Molding dimension) × 100, and the shrinkage rate of 5 times is (Dimension after heating once) − (Dimension after heating five times) / (Dimension after heating once) × It was calculated by the formula of 100. (6) Dimensional stability: Each evaluation sample was heated in a gear oven set at 135 ° C. for 1 hour, then left in a room at 22 ° C. ± 2 ° C. for 12 hours or more, and the longitudinal dimension was measured with a vernier caliper. This procedure was repeated five times to evaluate the dimensional change.

[0018]

[Table 2]

From the results shown in Table 2, the conductive compositions for injection molding according to the examples all have a heat distortion temperature exceeding 140 ° C.
Surface resistance value is 10 ⁵ Ω or less, volume resistivity is 1 × 10
^-6 or less, which indicates that the heat shrinkage rate of five times is lower than that of the comparative example, and that the dimensional stability is good.

[0020]

As described above, according to the present invention, dimensional shrinkage due to dimensional change due to heating after molding is quickly completed,
In addition, it is possible to provide a conductive resin composition for injection molding in which dimensional change due to repeated heating is extremely small. Therefore, it is expected to greatly contribute to, for example, the rationalization of the annealing step of the heat-resistant IC tray and the improvement of the quality.

Claims (1)

(57) [Claims] (1) 40 to 70% by weight of a polypropylene resin,
20-50% by weight of mica, carbon black having an average particle diameter of 100 mμ or less and an oil absorption of 50 ml / 100 g or more
A composition comprising 5 to 30% by weight and 0.1 to 3% by weight of an organic nucleating agent, and having a heat distortion temperature (ASTM D
-684: 4.6 kgf / cm ² ) having a characteristic of 140 ° C. or more and a volume resistivity (SRIS2301) of 1 × 10 ⁶ Ωcm or less, which is a conductive resin composition for injection molding.