JP5329804B2 - Mobile terminal parts - Google Patents

Description

  The present invention relates to a portable terminal component molded from a specific polybutylene terephthalate resin composition. More specifically, the present invention relates to a portable terminal component using a polybutylene terephthalate resin composition excellent in physical properties such as mechanical strength and impact strength, and moldability such as low sink and low warp deformation.

  There is a demand for miniaturization of various OA devices, home appliances, telephones, and other electrical / electronic devices, and in particular, there is a strong demand for compactness and lightness in electronic device products used as mobile phones. Conventionally, as a material for a housing (housing) for housing various portable terminal electronic devices and a reinforcing plate (chassis) for maintaining the strength of the product, aluminum, magnesium are used from the viewpoint of protecting the electronic devices. Such metal materials and ceramic materials have been used. However, the specific gravity of these materials, including 2.69 of aluminum, is quite large, so the proportion of the housing in the total weight of electronic equipment has become large, and it has become quite heavy. In addition, since metal materials are expensive and difficult to form, there are problems in terms of weight, cost, and productivity. In order to solve the above-mentioned problems that metal materials have, plastic materials with low specific gravity, low price, and excellent moldability have attracted attention as alternative materials.

  Since the specific gravity of a general plastic material is 2.0 or less, which is smaller than the specific gravity of a metal material, application to these parts can reduce the weight of a mobile terminal product. In addition, plastic materials are generally molded by methods such as compression molding, injection molding, injection-compression molding, blow molding, etc. Among them, injection molding methods are excellent in mass production, so that the cost can be reduced. Therefore, it is a molding technique most often used as a casing molding method for electronic devices. These portable terminals include polycarbonate (PC) resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, plastic material alone such as a blend material of ABS resin and polycarbonate resin or polybutylene terephthalate (PBT) resin, or carbon fiber. The use of composite materials filled with reinforcing materials such as glass fibers has been studied (Patent Document 1).

  However, the use of general plastic materials such as ABS resin, PC resin, ABS / PC resin, ABS / PBT resin alone is relatively low in mechanical strength such as tensile strength and elastic modulus, and impact characteristics. Therefore, there is a problem in that the number of parts increases and product design is restricted. On the other hand, for the purpose of improving mechanical strength, rigidity, and impact properties, composite materials reinforced with general glass fibers and carbon fibers have also been proposed, but the effect is not sufficient, especially with carbon fibers. Although the reinforced composite material has high rigidity, the material price is remarkably high, so it is not practical.

  In addition, a reinforced resin material using a blend material of aromatic polyamide resin and modified polyphenylene resin (Patent Document 2) has been proposed. However, with these resin materials, excellent strength and rigidity are obtained, but impact characteristics are insufficient, and a large amount of gas is generated at the time of molding, resulting in poor mass-productivity and the need for burr treatment that occurs in molded products. Therefore, there is a problem that the product manufacturing cost becomes high.

On the other hand, Patent Document 3 discloses a polybutylene terephthalate resin composition having excellent mechanical strength by using non-circular cross-section fibers having a longitudinal cross section as glass fibers. However, ordinary polybutylene terephthalate resin has a problem of large shrinkage that occurs during the solidification process during molding such as injection molding, resulting in a large amount of sink of the molded product and large warpage due to shrinkage anisotropy. It was. It has been considered difficult to apply to molded products that require high strength, high rigidity, high impact, sink marks and warp deformation of molded products at the same time as portable terminal components.
Japanese Patent Application Laid-Open No. 7-60777 JP-A-6-240132 Japanese Patent Laid-Open No. 62-268612

  An object of the present invention is to provide a portable terminal component comprising a polybutylene terephthalate resin composition which is excellent in physical properties such as mechanical strength and impact strength, and excellent in low sink and low warpage deformation.

As a result of intensive studies to solve the above problems, the present inventors have achieved the above object by molding a resin composition in which a specific modified polybutylene terephthalate resin and a glass fiber having a flat cross-sectional shape are combined. It has been found that portable terminal parts that can be achieved are obtained, and the present invention has been completed.
That is, the present invention
(A) For 100 parts by weight of the modified polybutylene terephthalate resin,
(B) A mobile terminal component comprising a polybutylene terephthalate resin composition formed by blending 40 to 140 parts by weight of glass fibers having a flat cross-sectional shape.

  A mobile terminal part made of the polybutylene terephthalate resin composition of the present invention has a high lightening effect and is resistant to breakage because it is resistant to rigidity and impact. Moreover, since the post-processing process is excellent because of excellent moldability, the manufacturing cost can be reduced. The present invention is suitable for a casing (housing), a reinforcing plate (chassis), a frame, a hinge, or a peripheral related component of a portable terminal component.

  Hereinafter, the constituent components of the resin material of the present invention will be described in detail.

  (A) Modified polybutylene terephthalate resin used in the present invention is (1) polybutylene terephthalate obtained by polycondensation reaction of terephthalic acid or its ester-forming derivative and 1,4-butanediol or its ester-forming derivative A copolymer in which 5 to 30 mol% of isophthalic acid is introduced as a comonomer unit, or a polybutylene terephthalate resin containing the copolymer, and (2) terephthalic acid or an ester-forming derivative thereof Polybutylene containing a modified polyethylene terephthalate copolymer comprising, as a main component, polyethylene terephthalate obtained by polycondensation reaction of ethylene glycol or an ester-forming derivative thereof, and 5 to 30 mol% of isophthalic acid as a comonomer unit. Terephthalate resin, (1), it may be a combination of combined isophthalic acid modified polybutylene terephthalate, the three isophthalic acid modified polyethylene terephthalate and polybutylene terephthalate (2).

  In both (1) and (2), isophthalic acid can be used for polycondensation in the form of an ester-forming derivative, for example, a lower alcohol ester such as dimethyl ester, and can be introduced as a copolymer component.

  Here, the introduction amount of the isophthalic acid comonomer unit is 5 to 30 mol%, preferably 10 to 30 mol%, particularly preferably 10 to 20 mol%. If the amount introduced is less than 5 mol%, the crystallinity is high, so that the anisotropy of molding shrinkage increases and warpage deformation increases. Further, when the introduction amount exceeds 30 mol%, the strength and thermal stability, which are the advantages of the original polybutylene terephthalate, are greatly reduced, and the crystallization is remarkably reduced and delayed, thereby reducing the molding cycle. There is a possibility that the mold releasability is lowered and a problem that is not practically used is caused.

  In the case of (1), either an isophthalic acid modified copolymer alone or a combination of an isophthalic acid modified copolymer and polybutylene terephthalate containing no isophthalic acid component can be used. In the case of combined use, it is necessary to contain 5 to 30 mol% of isophthalic acid component with respect to the total dicarboxylic acid component including the isophthalic acid-modified copolymer and polybutylene terephthalate not containing isophthalic acid component. For example, out of 100% by weight of the combined composition of polybutylene terephthalate whose carboxylic acid component consists only of terephthalic acid and 10 mol% isophthalic acid-modified copolymer, the proportion of polybutylene terephthalate is less than 50% by weight.

  In the case of (2), isophthalic acid-modified polyethylene terephthalate and polybutylene terephthalate are used in combination. In this case, it is necessary to contain 5-30 mol% of isophthalic acid components with respect to all dicarboxylic acid components in the modified polyethylene terephthalate. The proportion of isophthalic acid-modified polyethylene terephthalate is preferably 10 to 60% by weight when the combined amount of isophthalic acid-modified polyethylene terephthalate and polybutylene terephthalate is 100% by weight. If it is less than 10% by weight, the warp deformation suppressing effect is insufficient, and if it exceeds 60% by weight, the moldability as polybutylene terephthalate is impaired, and molding may not be possible at a mold temperature of 100 ° C. or less.

  (A) The modified polybutylene terephthalate resin is used as a copolymer copolymerized with a copolymerizable monomer (hereinafter sometimes referred to simply as a copolymerizable monomer) within a range not impairing the effects of the present invention. Can do. Examples of the copolymerizable monomer include dicarboxylic acid components excluding terephthalic acid and isophthalic acid, diols other than alkylene glycol having 2 to 4 carbon atoms, oxycarboxylic acid components, and lactone components. A copolymerizable monomer can be used 1 type or in combination of 2 or more types.

Dicarboxylic acids (or dicarboxylic acid components or dicarboxylic acids) include aliphatic dicarboxylic acids (for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, hexadecandioyl carboxylic acid, C _{4 to 40} dicarboxylic acids such as dimer acid, preferably C _{4 to 14} dicarboxylic acids), alicyclic dicarboxylic acid component (e.g., hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, hymic _C8-12 dicarboxylic acid such as acid), aromatic dicarboxylic acid components excluding terephthalic acid and isophthalic acid (for example, naphthalenedicarboxylic acid such as phthalic acid and 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid , 4,4'-Diphenoxyether dicarboxylic acid Acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4' C _{8 to 16} dicarboxylic acids such as diphenyl ketone dicarboxylic acid), or reactive derivatives thereof (e.g., lower alkyl Esters (such as C _1-4 alkyl esters of phthalic acid such as dimethylphthalic acid), derivatives capable of forming an ester such as acid chlorides and acid anhydrides) and the like. Furthermore, you may use together polyvalent carboxylic acid, such as trimellitic acid and pyromellitic acid, or its ester formation derivative (alcohol ester etc.) etc. as needed. When such a polyfunctional compound is used in combination, a branched polybutylene terephthalate resin can also be obtained.

Diols (or diol components or diols) include, for example, aliphatic alkanediols excluding 1,4-butanediol [for example, alkanediols (for example, ethylene glycol, trimethylene glycol, propylene glycol, neopentyl glycol, hexanediol ( 1,6-hexanediol, etc.), octanediol (1,3-octanediol, 1,8-octanediol, etc.), lower alkanediols such as decanediol, preferably linear or branched C _2-12 alkanes Diols, more preferably linear or branched C _2-10 alkane diols); (poly) oxyalkylene glycols (eg glycols having a plurality of oxy C _2-4 alkylene units, eg diethylene glycol, dipropylene glycol) Ditetramethylene glycol , Triethylene glycol, tripropylene glycol, polytetramethylene glycol, etc.)], alicyclic diols (eg, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.), aromatic Group diols [eg, dihydroxy C _6-14 arenes such as hydroquinone, resorcinol, naphthalenediol; biphenols (eg, 4,4′-dihydroxybiphenyl); bisphenols; xylylene glycol, etc.], and reactive derivatives thereof (eg, And ester-forming derivatives such as alkyl, alkoxy or halogen-substituted products). Furthermore, if necessary, a polyol such as glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, or an ester-forming derivative thereof may be used in combination. When such a polyfunctional compound is used in combination, a branched polybutylene terephthalate resin can also be obtained.

  In the copolymer, the proportion of the copolymerizable monomer can be selected, for example, from the range of about 0.01 to 30 mol%, and is usually 1 to 30 mol%, preferably 3 to 25 mol%, more preferably 5 to 5 mol%. It is about 20 mol% (for example, 5 to 15 mol%). In addition, when a homopolyester (polybutylene terephthalate) and a copolymer (copolyester) are used in combination, the proportion of the homopolyester and the copolyester is such that the proportion of the copolymerizable monomer is relative to the total monomers. The range is about 0.1 to 30 mol% (preferably 1 to 25 mol%, more preferably 5 to 25 mol%). Usually, the former / the latter = 99/1 to 1/99 (weight ratio), preferably It can be selected from a range of about 95/5 to 5/95 (weight ratio), more preferably about 90/10 to 10/90 (weight ratio).

  The modified polyethylene terephthalate resin can also be used as a copolymer copolymerized with a copolymerizable monomer other than isophthalic acid within a range not inhibiting the effects of the present invention.

  The intrinsic viscosity (IV) of the (A) modified polybutylene terephthalate resin is preferably 1.2 dL / g or less, more preferably 1.0 dL / g or less. By blending polybutylene terephthalate resins or modified polyesters with different intrinsic viscosities, for example by blending polybutylene terephthalate resins with intrinsic viscosities of 1.2 dL / g and 0.8 dL / g, an intrinsic viscosity of 1.0 dL / g or less is achieved. It may be realized. The intrinsic viscosity (IV) can be measured, for example, in O-chlorophenol at a temperature of 35 ° C. When a polybutylene terephthalate resin having an intrinsic viscosity in such a range is used, it is easy to efficiently achieve sufficient toughness and a reduced melt viscosity. If the intrinsic viscosity is too large, the melt viscosity at the time of molding becomes high, and in some cases, there is a possibility of causing poor resin flow and poor filling in the molding die.

  (B) The glass fiber having a flat cross-sectional shape used in the present invention is a long diameter (longest linear distance in the cross section) and a short diameter (longest straight distance in the direction perpendicular to the long diameter). Is a glass fiber having a ratio of 1.3 to 10, preferably 1.5 to 8, particularly preferably 2 to 5. Specific shapes include a substantially oval shape, a substantially oval shape, a substantially eyebrow shape, and the like.

  (B) The glass fiber having a flat cross-sectional shape is excellent in mechanical strength and impact strength, suppresses warpage deformation, and is excellent in moldability.

  The glass fiber having a flat cross-sectional shape preferably has an average cross-sectional area of 100 to 300 square micrometers. If it is smaller than 100 square micrometers, the mechanical strength and impact strength are not sufficient, and if it exceeds 300 square micrometers, problems such as gate clogging during injection molding and wear of molds and molding machines occur.

  The blending amount of the glass fiber (B) having a flat cross-sectional shape used in the present invention is 40 to 140 parts by weight, preferably 50 to 130 parts by weight, with respect to 100 parts by weight of the (A) modified polybutylene terephthalate resin. . When the blending amount is less than 40 parts by weight, the mechanical strength and impact strength are low, and when it exceeds 140 parts by weight, the fluidity is remarkably deteriorated.

  (B) In using a glass fiber having a flat cross-sectional shape, it is desirable to use a sizing agent or a surface treatment agent if necessary. If this example is shown, all functional compounds, such as an epoxy-type compound, an acryl-type compound, an isocyanate type compound, a silane type compound, and a titanate type compound, are used preferably. These compounds may be used after surface treatment or convergence treatment in advance, or may be added at the same time as the material preparation. Moreover, the usage-amount of the functional surface treating agent used together is 0 to 10 weight% with respect to a filler, Preferably it is 0.01 to 5 weight%.

  Such glass fiber (B) can be used regardless of the form of glass fiber at the time of blending A glass, E glass, an alkali-resistant glass composition containing a zirconia component, chopped strand, roving glass or the like.

  (B) The glass fiber having a flat cross-sectional shape used in the present invention uses a nozzle having an appropriate hole shape such as an oval, an ellipse, a rectangle, or a slit as a bushing used for discharging molten glass. Prepared by spinning. Also prepared by spinning molten glass from a plurality of adjacent nozzles having various cross-sectional shapes (including circular cross-sections), and joining the spun molten glass into a single filament it can.

  In mobile terminal parts, resin materials may be colored and used. In this case, it is common to use an inorganic white pigment together with various colored pigments and dyes. As the inorganic white pigment optimal for the resin composition of the present invention, (C) inorganic white pigment having a Mohs hardness of 4.5 or less, such as zinc sulfide, zinc oxide, barium sulfate, lithopone, magnesium carbonate, muscovite, calcium sulfate, barite , Calcium carbonate and the like. With these white pigments, good physical properties can be obtained because glass fiber breakage is small. On the other hand, rutile-type titanium oxide, anatase-type titanium oxide, brookite-type titanium oxide and the like having a Mohs hardness exceeding 4.5 are not preferable because many glass fiber breaks may occur. The blending amount of the inorganic white pigment is not particularly limited as long as it is a general coloring requirement amount.

  In addition, the resin composition of this invention may contain other resin in the range which does not impair the effect of this invention as needed. Other resins include polyester resins other than polybutylene terephthalate resins (polyethylene terephthalate, polytrimethylene terephthalate, etc.), polyolefin resins, polystyrene resins, polyamide resins, polyacetals, polyarylene oxides, polyarylene sulfides, fluorine resins, etc. Is exemplified. Further, copolymers such as acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin, and ethylene-ethyl acrylate resin are also exemplified. These other resins may be used alone or in combination of two or more.

  Moreover, you may add various additives (a stabilizer, a moldability improving agent, etc.) to the resin composition of this invention. Examples of additives include various stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), nucleating agents (crystallization nucleating agents), flame retardants, lubricants, mold release agents, antistatic agents, dyes / pigments, etc. Colorants, dispersions, and the like.

  In particular, when a polybutylene terephthalate and a polyester having different alkylene glycol components such as polycarbonate and polyethylene terephthalate are used in combination, it is preferable to add a phosphorus-based stabilizer to suppress transesterification. Examples of the phosphorus stabilizer used include organic phosphite compounds, phosphonite compounds, and metal phosphates. Specific examples include bis (2,4-di-t-4methylphenyl) pentaerythritol diphosphite, bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tetrakis (2,4 Examples of the -di-t-butylphenyl) -4,4'-biphenylene phosphonite and metal phosphate include monobasic calcium phosphate, monobasic sodium phosphate hydrate, and the like.

  It should be noted that other reinforcing fillers can be added to the resin composition of the present invention as needed within a range not impairing the effects of the present invention. Other reinforcing fillers include glass fibers other than those specified in the present invention, milled glass fibers, glass beads, glass flakes, silica, alumina fibers, zirconia fibers, potassium titanate fibers, carbon fibers, graphite, calcium silicate, Silicates such as aluminum silicate, kaolin, talc and clay, metal oxides such as iron oxide, titanium oxide, zinc oxide, antimony oxide and alumina, carbonates and sulfates of metals such as calcium, magnesium and zinc, and carbonization Examples of the organic filler include silicon polyester, silicon nitride, boron nitride and the like, and examples of the organic filler include high melting point aromatic polyester fiber, liquid crystalline polyester fiber, aromatic polyamide fiber, fluororesin fiber, and polyimide fiber.

  The composition of the present invention is easily prepared by equipment and methods generally used as conventional resin composition preparation methods. For example, after mixing each component, kneading and extruding with a single-screw or twin-screw extruder to prepare pellets, then forming the pellets, once preparing pellets with different compositions, mixing the pellets in a predetermined amount Any method can be used, such as a method of obtaining a molded product having a desired composition after molding and a method of directly charging one or more of each component into a molding machine. Further, mixing a part of the resin component as a fine powder with other components and adding it is a preferable method for uniformly blending these components. Injection molding, extrusion molding, compression molding, blow molding, vacuum molding, rotational molding, gas injection molding, etc. can be applied as a molding method for filling the resin into the mold, but injection molding is common. .

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.
Examples 1-8, Comparative Examples 1-7
Each resin composition was dry blended at the mixing ratio shown in Table 1, and melt-kneaded at a cylinder set temperature of 250 ° C. using a twin-screw extruder (manufactured by Nippon Steel Co., Ltd.) having a 30 mmφ screw. Test pieces were prepared and evaluated. The results are shown in Table 1.

Moreover, the detail of the used component and the measuring method of physical property evaluation are as follows.
(1) Components used
(A) component
(A-1) Isophthalic acid modified polybutylene terephthalate (Intrinsic viscosity IV = 0.65dL / g)
Modified polybutylene terephthalate using 12.5 mol% of dimethylisophthalic acid as a copolymer component instead of a part of terephthalic acid (12.5 mol%) in the reaction of terephthalic acid with 1,4-butanediol
(A-2) Polybutylene terephthalate (Intrinsic viscosity IV = 0.69 dL / g, manufactured by Wintech Polymer Co., Ltd.)
(A-3) Isophthalic acid-modified polyethylene terephthalate (modified with 12.0 mol% isophthalic acid, intrinsic viscosity IV = 0.80 dL / g, manufactured by Bell Polyester Products)
(B) Glass fiber
(B-1): Glass fiber having a flat cross-sectional shape (ratio of major axis / minor axis: 4, average sectional area 196 μm ² , manufactured by Nittobo Co., Ltd.)
(B'-1): Glass fiber having a general circular cross-sectional shape (major axis / minor axis ratio: 1, average cross-sectional area of 133 μm ² , manufactured by NEC Glass, Inc.)
(C) White pigment
(C-1) Zinc sulfide Mohs hardness 4
(C'-1) Rutile type titanium oxide Mohs hardness 7
In Examples 6, 7, 8 and Comparative Example 5, 0.15 parts by weight of primary calcium phosphate was further added to the composition in the table.
(2) Physical property evaluation <Tensile strength>
The obtained pellets were dried at 140 ° C. for 3 hours, then a tensile test piece was prepared by injection molding at a molding machine cylinder temperature of 260 ° C. and a mold temperature of 80 ° C., and measured according to ISO-527 (test piece thickness 4 mm). did.
<Charpy impact strength>
The obtained pellets were dried at 140 ° C. for 3 hours, then a Charpy impact test piece was produced by injection molding at a molding machine cylinder temperature of 260 ° C. and a mold temperature of 80 ° C., according to ISO-179 (test piece thickness 4 mm). It was measured.
(3) Evaluation of warpage deformation The flatness of the flat plate was measured according to the following criteria.
Evaluation molded product; 50mm x 50mm x 1mm thickness flat plate molding machine; FANUC ROBOSHOTα-100Ia
Cylinder temperature: 260-260-240-220 ℃
Mold temperature: 80 ℃
Injection pressure: 69MPa
Flatness measuring machine; CNC image measuring machine Quick Vision QVH404 (Mitutoyo)
The flatness measurement method was performed at 9 points (3 × 3 points in length and width) on a flat plate.
(4) Evaluation in mobile phone housing The mobile phone housing shown in FIG. 1 was molded, and (4-1) to (4-3) were evaluated.
Molding machine: Sumitomo Heavy Industries SE100D
Cylinder temperature: 270-270-260-230 ℃
Mold temperature: 100 ℃
(4-1) Bending strength of hinge portion of mobile phone housing The bending strength was measured by bending the hinge portion of FIG.

Measuring instrument: Universal testing machine Tensilon UTA50KN (Orientec)
Measurement speed: 1000mm / min
(4-2) Sink on the boss part of the mobile phone housing Sink condition on the surface of the boss part in FIG. 1 was visually observed.
Judgment ○… Low sink × × High sink
(4-3) Burning of mobile phone housing (compression heat generated by gas)
The burn condition at the flow end of the hinge part in FIG. 1 was visually observed.
Judgment ○… less burnt ×… more burnt

It is a figure which shows the mobile telephone housing shape | molded in the Example, and its evaluation condition.

Claims (3)

(A) Based on 100 parts by weight of an isophthalic acid- modified polybutylene terephthalate resin containing 5 to 30 mol% of isophthalic acid based on the total dicarboxylic acid component ,
(B) Ri greens by blending glass fibers 40 to 140 parts by weight having a flat cross section,
(B) The ratio of the long diameter (longest straight line distance in the cross section) to the short diameter (long straight line and longest straight distance in the right angle direction) is 1.3 to 10 in the glass fiber having a flat cross-sectional shape. A portable terminal component comprising a polybutylene terephthalate resin composition having an average cross-sectional area of 100 to 300 square micrometers . The polybutylene terephthalate resin composition has further contain (C) Mohs hardness below 4.5 inorganic white pigment, wherein (C) a mobile terminal part of the colored claim 1, wherein using the components. Mobile terminal part of the casing (housing), the reinforcing plate (chassis), a frame, a hinge or a portable terminal component according to claim 1 or 2 wherein the these peripheral related parts.

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