JP2011132342A - Housing for personal digital assistant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a housing for a personal digital assistant that has a beautiful, profound and high-quality piano black-like external appearance, achieves excellent productivity owing to high flowability, and also exhibits excellent drop impact resistance while retaining excellent performances inherent in a polycarbonate resin such as impact strengths, heat resistance, thermal stability and the like. <P>SOLUTION: The housing for a personal digital assistant is obtained by molding a polycarbonate resin composition, where the polycarbonate resin composition is one comprising as essential ingredients a specific polycarbonate resin, an organic black dye and a cyclic poly(alkylene terephthalate) oligomer. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a housing for a portable information terminal made of a polycarbonate resin composition that is excellent in jet blackness and excellent in fluidity, drop impact property, scratch resistance, and releasability. More specifically, while maintaining the impact resistance, heat resistance, thermal stability, etc. that are the characteristics of polycarbonate resin, a portable information terminal having excellent jet blackness, fluidity, drop impact resistance, scratch resistance, and releasability Related to housing. The portable information terminal housing of the present invention has a beautiful, heavy and high quality appearance.

  Polycarbonate resin is a thermoplastic resin excellent in impact resistance, heat resistance, thermal stability, and the like, and is widely used in fields such as electricity, electronics, ITE, machinery, and automobiles. On the other hand, the housing for portable information terminals has excellent jetness from the viewpoint of the design and design of the obtained molded product while taking advantage of these excellent performances of the resin (also called piano black). Appearance is desired.

  As a technique for imparting jet blackness to a polycarbonate resin composition, a technique for adding carbon black having high concealment (Patent Document 1), a technique for adding silicone oil (Patent Document 2), and the like have been proposed. However, when a carbon black pigment is added, it is difficult to develop high jetness although the concealability is improved. On the other hand, the addition of silicone oil has a problem of whitening during molding.

JP2003-96286 JP 2004-210889 A

  On the other hand, polycarbonate resin is a resin with excellent impact resistance, but in recent applications for housings for personal digital assistants that require lightness, thinness, there are many thin molded products, in addition to problems such as cracking and breakage when the product is dropped. In particular, improvement in fluidity during molding and scratching on the surface of the molded product is particularly demanded.

  The object of the present invention is to overcome the above-mentioned problems in the prior art, that is, to overcome the disadvantages of jet black deterioration and whitening when using carbon black or silicone oil, An object of the present invention is to provide a housing for a portable information terminal made of polycarbonate resin that has a piano black-like appearance) and is excellent in fluidity, drop impact property, and scratch resistance.

  As a result of diligent research in view of such an object, the present inventors have found that an organic black dye and a cyclic poly (alkylene terephthalate) oligomer having specific optical performance in a polycarbonate resin having transparency, and, if necessary, a rubber component. By blending, the appearance of a piano black can be obtained without impairing the jetness of the obtained molded product, and it has been found that not only the fluidity but also the impact resistance when dropped can be improved, and the present invention is completed. It came to.

That is, the present invention is a housing for a portable information terminal formed by molding a polycarbonate resin composition,
(1) The polycarbonate resin composition comprises 100 parts by weight of a polycarbonate resin (A) having a viscosity average molecular weight of 17,000 to 24,000, 0.05 to 0.5 parts by weight of an organic black dye (B), and cyclic poly (alkylene terephthalate). It consists of a resin composition containing 1 to 8 parts by weight of oligomer (C) as an essential component,
(2) The optical characteristics of the organic black dye (B) were obtained by injection molding a resin composition comprising 100 parts by weight of the polycarbonate resin (A) and 0.3 parts by weight of the organic black dye (B). When measuring the light transmittance of a flat plate with a thickness of 2 mm, it has a light transmittance of 50% or more in a wavelength region of 800 to 900 nm,
(3) When the flow length at a flow path thickness of 1 mm was measured using an Archimedes spiral flow mold under the conditions of a melting temperature of 280 ° C. and an injection pressure of 1600 kg / cm ² , the flow length was measured. When the impact strength with a notch is measured according to ASTM D-256 using a 3.2 mm test piece obtained by injection molding the polycarbonate resin composition. , Having an impact resistance of 600 J / m or more,
The present invention provides a housing for a portable information terminal.

  The housing for portable information terminals of the present invention has a piano black-like appearance that is beautiful, heavy, and high-quality while maintaining the excellent impact strength, heat resistance, thermal stability, etc. inherent to the polycarbonate resin, and Excellent fluidity due to high fluidity, and excellent impact resistance when dropped.

  The polycarbonate resin (A) used in the present invention is obtained by a phosgene method in which various dihydroxydiaryl compounds and phosgene are reacted, or a transesterification method in which a dihydroxydiaryl compound and a carbonate such as diphenyl carbonate are reacted. A typical example of the polymer is a polycarbonate resin produced from 2,2-bis (4-hydroxyphenyl) propane (commonly referred to as bisphenol A).

  Examples of the dihydroxydiaryl compound include bisphenol 4-, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2, 2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxyphenyl-3-methylphenyl) propane, 1,1-bis (4-hydroxy-3) -Tert-butylphenyl) propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis ( Bis (hydroxyaryl) alkanes such as 4-hydroxy-3,5-dichlorophenyl) propane, 1,1- (4-hydroxyphenyl) cyclopentane, bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3 Dihydroxy diaryl ethers such as 3,3'-dimethyldiphenyl ether, dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3 ' Dihydroxy diaryl sulfoxides such as dimethyldiphenyl sulfoxide, dihydroxy diary such as 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone Sulfone, and the like.

  These may be used alone or in combination of two or more. In addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4′-dihydroxydiphenyl, and the like may be used in combination.

  Furthermore, the above dihydroxyaryl compound and a trivalent or higher valent phenol compound as shown below may be used in combination. Trihydric or higher phenols include phloroglucin, 4,6-dimethyl-2,4,6-tri- (4-hydroxyphenyl) -heptene, 2,4,6-dimethyl-2,4,6-tri- (4 -Hydroxyphenyl) -heptane, 1,3,5-tri- (4-hydroxyphenyl) -benzol, 1,1,1-tri- (4-hydroxyphenyl) -ethane and 2,2-bis- [4 4- (4,4'-dihydroxydiphenyl) -cyclohexyl] -propane and the like.

   The viscosity average molecular weight of the polycarbonate resin (A) is 17000 to 24000. When the viscosity average molecular weight is less than 17,000, the drop impact strength is inferior, and when it exceeds 24,000, the fluidity is inferior. Preferably, it is in the range of 18000 to 23000, more preferably 19000 to 22000.

The viscosity average molecular weight of the polycarbonate resin (A) was determined by measuring the specific viscosity (η _sp ) at a temperature of 20 ° C. using a Cannon-Fenske type viscosity tube with a 0.5% by weight polycarbonate resin solution using methylene chloride as a solvent. The intrinsic viscosity [η] was obtained by conversion and calculated from the following SCHNELL formula.
[Η] = 1.23 × 10 ⁻⁴ M ^0.83

  Examples of the organic black dye (B) used in the present invention include a mixture of organic dyes such as anthraquinone, perinone, perylene, azo, methine, and xylinone. In particular, anthraquinone-based and perinone-based organic dyes are preferably used. Anthraquinone-based organic dyes such as blue, purple and green are preferable, and perinone-based organic dyes such as red and orange are preferable.

  The organic black dye (B) of the present invention is obtained by injection molding a resin composition comprising 100 parts by weight of a polycarbonate resin (A) and 0.3 part by weight of an organic black dye (B) as its optical characteristics. When measuring the light transmittance of a flat plate having a thickness of 2 mm, it is necessary to have a light transmittance of 50% or more in a wavelength region of 800 to 900 nm. The light transmittance is measured according to ASTM D-1003.

  When the light transmittance is less than 50%, an excellent jet black (piano black-like) appearance cannot be obtained, which is not preferable. The light transmittance is preferably 80% or more, more preferably 85% or more.

  Moreover, as a compounding quantity of organic type black dye (B), it is 0.05-0.5 weight part with respect to 100 weight part of polycarbonate resin (A). If the blending amount is less than 0.05 parts by weight, jet blackness and hiding properties are inferior. If the blending amount exceeds 0.5 parts by weight, the thermal stability of the polycarbonate resin (A) is inferior. This is not preferable. A more preferable blending amount is in the range of 0.1 to 0.4 parts by weight, and more preferably 0.2 to 0.3 parts by weight.

The cyclic poly (alkylene terephthalate) oligomer (C) used in the present invention means one having a structural unit represented by the following general formula.

  In the formula, R represents an alkylene group having 2 to 8 carbon atoms, and Ar represents a divalent aromatic group. In particular, those in which R is ethylene or tetramethylene and Ar is m-phenylene or p-phenylene are preferably used.

  The cyclic poly (alkylene terephthalate) oligomer (C) is usually a mixture of cyclic oligomers having a polymerization degree of 2 to 30 and the main component having a polymerization degree of up to 12. Commercially available products include CBT manufactured by Cyclix Corporation.

  The compounding quantity of cyclic poly (alkylene terephthalate) oligomer (C) is 1-8 weight part with respect to 100 weight part of polycarbonate resin (A). If the blending amount is less than 1 part by weight, the effect of improving scratch resistance is small, and if it exceeds 8 parts by weight, the impact strength decreases and the appearance of the molded product also decreases, which is not preferable. More preferably, it is in the range of 2 to 5 parts by weight.

  The rubber component (D) used in the present invention includes acrylonitrile-butadiene-styrene copolymer (ABS resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin), high impact polystyrene (HIPS) and the like. And rubber reinforced styrene copolymers, acrylic or silicone elastomers, and the like.

  The compounding quantity of a rubber component (D) is 1-8 weight part with respect to 100 weight part of polycarbonate resin (A). If the blending amount is less than 1 part by weight, the drop impact strength is small, and if it exceeds 8 parts by weight, jet blackness is lowered, which is not preferable. More preferably, it is in the range of 2 to 5 parts by weight.

  The blending method of the various blending components (A), (B) and (C) of the present invention, and (D) depending on necessity is not particularly limited. And then kneading and kneading with a normal single-screw or twin-screw extruder. Moreover, there is no restriction | limiting in particular also about employ | adopting batch mixing and division | segmentation mixing for these compounding components.

  In addition, other known additives such as mold release agents, UV absorbers, antistatic agents, antioxidants, phosphorous heat stabilizers, spreading agents (epoxy soybean oil, liquid paraffin, etc.) may be used at the time of mixing. ) And the like.

  As a method for manufacturing the housing for a portable information terminal of the present invention, methods such as injection molding, injection compression molding, and injection press molding can be employed.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Parts and% are based on weight unless otherwise specified.

The details of the used blending components are as follows.
Polycarbonate resin:
Polycarbonate resin synthesized from bisphenol A and phosgene Sumitomo Dow Caliber 200-13
(Viscosity average molecular weight: 21000, hereinafter abbreviated as PC1)
Sumitomo Dow Caliber 200-40
(Viscosity average molecular weight: 16500, hereinafter abbreviated as PC2)
Caliber 200-4 manufactured by Sumitomo Dow
(Viscosity average molecular weight: 26000, hereinafter abbreviated as PC3)
Organic black dye:
Sumiplast Black HB
(Manufactured by Sumika Chemtex Co., Ltd., hereinafter abbreviated as Colorant 1)
Light transmittance in a wavelength range of 800 to 900 nm * 1: 85%
Sumiplast Black HLG
(Manufactured by Sumika Chemtex Co., Ltd., hereinafter abbreviated as Colorant 2)
Light transmittance in the wavelength region of 800 to 900 nm * 1: 55%
Carbon black:
Furnace type carbon black (XC-305 manufactured by Cabot, hereinafter abbreviated as Colorant 3)
Light transmittance in a wavelength region of 800 to 900 nm * 1: Less than 1% * 1: The light transmittance is injection-molded with a resin composition comprising 100 parts of PC1 and 0.3 parts of colorant 1, 2 or 3. Using the 2 mm thick flat plate obtained in this way,
Measurement was performed in a wavelength range of 800 to 900 nm in accordance with D-1003.
Cyclic poly (alkylene terephthalate) oligomer:
Cyclic poly (butylene terephthalate) oligomer (CBT manufactured by Axia Materials, hereinafter abbreviated as CBT)
Rubber component:
Acrylonitrile-butadiene-styrene copolymer (ABS resin)
(Nippon A & L Co., Ltd. Clarastic S3710, hereinafter abbreviated as ABS)

(Preparation of polycarbonate resin composition pellets)
The above-mentioned various blending components are collectively put into a tumbler at the blending ratios shown in Tables 1 to 3, and after dry mixing for 10 minutes, using a twin screw extruder (KTX37 manufactured by Kobe Steel), a melting temperature of 280 ° C. Kneaded to obtain various pellets of the polycarbonate resin composition.

(Create test pieces for evaluating jetness, scratching and impact strength)
The obtained pellets of various resin compositions were dried at 120 ° C. for 4 hours, and then jet jet under conditions of a cylinder temperature of 280 ° C. and a mold temperature of 100 ° C. using an injection molding machine (J100E-C5 manufactured by Nippon Steel Works). A flat plate (90 × 50 × 2 mm) was used for evaluation of optical properties and scratches, and an ASTM Izod impact test piece (3.2 mm thickness) was used for evaluation of impact strength.

(Creation of test specimen for drop test evaluation)
The obtained pellets of various resin compositions were dried at 120 ° C. for 4 hours, and then box-shaped under conditions of a cylinder temperature of 280 ° C. and a mold temperature of 120 ° C. using an injection molding machine (J100E-C5 manufactured by Nippon Steel Works). A molded product (150 × 30 × 20 mm, main wall thickness 2 mm) was prepared.

(Evaluation of jetness)
The evaluation of jetness is performed by irradiating the obtained 2 mm flat plate with the light of the LED light source (GETROS GTR-32T, brightness 26.6 lumens) (the distance between the light of the flat plate and the LED light source is 10 cm). The degree of jetness was evaluated. The results are shown in Tables 1-3.
The evaluation criteria are as follows:
Good (◎): Even when illuminated by an LED light source, it glows black.
Good (◯): Even if the LED light source is irradiated, it glows black, but looks slightly whitish.
Defect (x): When an LED light source is irradiated, it glows whitish.

(Evaluation of impact strength)
The impact strength was determined by measuring the notched Izod impact strength (J / m) under the condition of 23 ° C. using the obtained Izod impact test piece in accordance with ASTM D-256. 600 J / m or more was considered acceptable. The results are shown in Tables 1-3.

(Evaluation of drop strength)
The drop strength is the extent of damage by attaching a weight to the inside of the box so that the total weight is 1 kg, and dropping it onto a lauan material with a thickness of 75 cm to a thickness of 14 mm. It was evaluated by observing. Specifically, it is allowed to drop naturally so that the first 6 faces of the molded product, then 3 sides from the predetermined corner, and finally 1 corner (1 side, 3 sides, 6 faces) of the corner corresponds to the raw material. A total of 10 drop tests were taken as one cycle.
A crack that occurred on the surface of the molded product or a crack that resulted in a fractured surface was rejected. A deformation that retained the shape of the box was accepted, and three cycles or more were accepted. The results are shown in Tables 1-3.

(Evaluation of scratchability)
The evaluation of scratchability was performed as follows.
(1) One commercially available tissue paper is spread and folded five times, and a total of 32 laminates are prepared in advance.
(2) Prepare a jig (stainless steel, height 15 mm x width 15 mm x depth 10 mm, R3 mm saddle) with a linear pressure section of 15 mm, and wind the laminated tissue paper around the jig Put on.
(3) The jig around which the tissue paper obtained in the above (2) is wound is brought into contact with the surface of a flat plate (90 × 50 × 2 mm) for evaluation of scratching property, and a total of 250 g of the tissue is placed on the tissue. After adjusting to become a load, it is reciprocated 50 times at a speed of 50 mm / sec.
(4) Thereafter, the presence or absence of scratches generated on the surface of the flat plate was visually observed and evaluated according to the following criteria.
Good (◎): Good without any scratches.
Good (O): Although there are some scratches, it is not whitened.
Defect (x): The surface is whitened and looks whitish. Or the surface is scratched.
(5) The surface was not whitened or scratched.

(Evaluation of liquidity)
The flow length at a channel thickness of 1 mm was measured using an Archimedes spiral flow mold under the conditions of a melting temperature of 280 ° C. and an injection pressure of 1600 kg / cm ² . A flow length of 110 mm or more was regarded as acceptable.

  When the polycarbonate resin composition satisfied all the constituent requirements of the present invention (Examples 1 to 7), good results were exhibited over all the evaluation items.

On the other hand, in the case where the polycarbonate resin composition does not satisfy the constituent requirements of the present invention, each case has some drawbacks.
Comparative Example 1 was inferior in jet blackness because the blending amount of the organic black dye was less than the specified amount.
In Comparative Example 2, since the blending amount of the organic black dye was larger than the specified amount, the impact strength and the drop strength were reduced.
Since the comparative example 3 used carbon black for the coloring agent, it was inferior in jetness.
In Comparative Example 4, since the blending amount of CBT was less than the prescribed amount, the scratch resistance and fluidity were inferior.
Comparative Example 5 was inferior in impact strength and drop strength because the blending amount of CBT was larger than specified.
Comparative Example 6 was inferior in impact strength and drop strength because the viscosity average molecular weight of the polycarbonate resin was lower than specified.
Comparative Example 7 was inferior in fluidity because the viscosity average molecular weight of the polycarbonate resin was higher than specified.
Comparative Example 8 was inferior in jet blackness, impact strength, drop strength, and scratch resistance because the blending amount of ABS was larger than specified.

Claims (6)

A portable information terminal housing formed by molding a polycarbonate resin composition,
(1) The polycarbonate resin composition comprises 100 parts by weight of a polycarbonate resin (A) having a viscosity average molecular weight of 17,000 to 24,000, 0.05 to 0.5 parts by weight of an organic black dye (B), and cyclic poly (alkylene terephthalate). It consists of a resin composition containing 1 to 8 parts by weight of oligomer (C) as an essential component,
(2) The optical characteristics of the organic black dye (B) were obtained by injection molding a resin composition comprising 100 parts by weight of the polycarbonate resin (A) and 0.3 parts by weight of the organic black dye (B). When measuring the light transmittance of a flat plate with a thickness of 2 mm, it has a light transmittance of 50% or more in a wavelength region of 800 to 900 nm,
(3) When the flow length at a flow path thickness of 1 mm was measured using an Archimedes spiral flow mold under the conditions of a melting temperature of 280 ° C. and an injection pressure of 1600 kg / cm ² , the flow length was measured. When the impact strength with a notch is measured according to ASTM D-256 using a 3.2 mm test piece obtained by injection molding the polycarbonate resin composition. , Having an impact resistance of 600 J / m or more,
A portable information terminal housing.   The optical characteristics of the organic black dye (B) are 2 mm thick obtained by injection molding a resin composition comprising 100 parts by weight of the polycarbonate resin (A) and 0.3 parts by weight of the organic black dye (B). The portable information terminal housing according to claim 1, which has a light transmittance of 80% or more in a wavelength range of 800 to 900 nm when the light transmittance of the flat plate is measured.   The optical characteristics of the organic black dye (B) are 2 mm thick obtained by injection molding a resin composition comprising 100 parts by weight of the polycarbonate resin (A) and 0.3 parts by weight of the organic black dye (B). The housing for a portable information terminal according to claim 1, which has a light transmittance of 85% or more in a wavelength region of 800 to 900 nm when the light transmittance of the flat plate is measured.   The housing for a portable information terminal according to claim 1, wherein the cyclic poly (alkylene terephthalate) oligomer (C) is a cyclic poly (butylene terephthalate) oligomer.   The rubber component (D) is added to the polycarbonate resin composition in an amount of 1 to 8 parts by weight (per 100 parts by weight of the polycarbonate resin (A)), according to any one of claims 1 to 4. Housing for portable information terminals.   6. The personal digital assistant housing according to claim 5, wherein the rubber component (D) is acrylonitrile-butadiene-styrene resin.