JP5767850B2 - Thin molded body for electronic device housing - Google Patents

Description

  The present invention relates to a thin molded article suitable for use in an electronic device housing such as a mobile phone or an internal chassis, and a method for manufacturing the same.

  An electronic device housing such as a cellular phone and an internal chassis are made of a thin molded body, and are required to have a high flexural modulus, excellent impact resistance, and a small dimensional change due to water absorption.

  Patent Document 1 discloses a polyamide molding compound composed of polyamide, a filler, an additive and an auxiliary agent, and describes a casing or casing of a mobile phone as its use. The filler contains flat glass fibers.

In Patent Document 2, 50 to 100 mol of a dicarboxylic acid unit (a) containing 50 to 100 mol% of a terephthalic acid unit, 1,9-nonanediamine unit and / or 2-methyl-1,8-octanediamine unit. % Long-fiber reinforced half containing 100 parts by mass of semi-aromatic polyamide resin (A) composed of diamine unit (b) and 5 to 300 parts by mass of fibrous reinforcing material (B) having a fiber length of 3 mm or more. An aromatic polyamide resin composition is disclosed.
It is described that the weight average fiber length of the fibrous reinforcing material (B) in the molded product is preferably 1 to 10 mm (paragraph number 42). In Example 3 (paragraph number 67), glass in the molded product is described. It is described that the weight average fiber length of the fiber is 3 to 5 mm. Thus, since the fiber length in a molded product is long, the use of a thin molded body (a molded body having a thickness of 2 mm or less) is not described (paragraph number 43).

JP 2009-79212 A JP 2006-274061 A

  The present invention is a thin-walled molded article having a thickness of 0.8 to 2.0 mm, which is suitable for a housing of an electronic device such as a mobile phone or an internal chassis, and has a high mechanical strength and a small dimensional change due to water absorption. It aims at providing a molded object and its manufacturing method.

As a means for solving the problems, the present invention
Including a resin-impregnated fiber bundle that is bundled in a state in which the glass long fibers are aligned in the length direction, impregnated in a state where the polyamide is melted in the bundle of glass long fibers, and then cut to a length of 5 to 15 mm. A thin molded article obtained from the resin composition,
The polyamide in the resin-impregnated fiber bundle is a polyamide obtained from an aromatic dicarboxylic acid and an aliphatic diamine or a polyamide obtained from an aliphatic dicarboxylic acid and an aromatic diamine,
Provided is a thin molded article having a glass fiber content in the resin-impregnated fiber bundle of 40 to 70% by mass and satisfying the following requirements (a) to (d).
(A) The thickness of the thin molded body is 0.8 to 2.0 mm.
(B) The weight average fiber length of the glass fiber in the thin molded article is 0.5 to 1.5 mm.
(C) Charpy impact strength of the thin-walled molded product is 10 kJ or more. (D) The absolute dry value of the bending elastic modulus (length 80 mm × width 10 mm × thickness 2 mm test piece) of the thin-walled molded product is used as the standard (100%). When the moisture absorption value is 80% or more

  The thin molded article of the present invention has a high mechanical strength despite its extremely thin thickness of 0.8 to 2.0 mm, and is in a saturated water absorption state in an atmosphere of 23 ° C./50% RH. However, the dimensional change is very small. The thin molded article of the present invention is suitable for various electronic equipment housings and internal chassis.

Explanatory drawing of the measuring method of the dimensional-change rate by water absorption.

<Resin composition>
The resin-impregnated fiber bundle contained in the resin composition used in the present invention is obtained by bundling long glass fibers in a state in which they are aligned in the length direction, and after impregnating and integrating the polyamide long fibers in a bundle of the long glass fibers. , Cut to a length of 5 to 15 mm. The length of the glass fiber contained in the resin-impregnated fiber bundle is the same as the length of the resin-impregnated fiber bundle.

  The polyamide contained in the resin-impregnated fiber bundle is obtained from a polyamide obtained from an aromatic dicarboxylic acid and an aliphatic diamine or from an aliphatic dicarboxylic acid and an aromatic diamine.

  Specific examples include a polymer of hexamethylene diamine and terephthalic acid (nylon 6T), a polymer of hexamethylene diamine and isophthalic acid (nylon 6I), and a polymer of hexamethylene diamine and terephthalic acid and isophthalic acid (nylon 6T / 6I). , Polymer of hexamethylenediamine and adipic acid and terephthalic acid, polymer of hexamethylenediamine and terephthalic acid and ε-caprolactam, polymer of metaxylylenediamine and adipic acid (nylon MXD-6), trimethylhexamethylenediamine Polymer of terephthalic acid (nylon TMD-6), polymer of trimethylhexamethylenediamine, terephthalic acid and ε-caprolactam, polymer of trimethylhexamethylenediamine, terephthalic acid and isophthalic acid, terephthalic acid and isophthalic acid and hexamethyle Diamine and ε-caprolactam polymer, metaxylylenediamine and terephthalic acid and isophthalic acid and ε-caprolactam copolymer, nonanediamine and terephthalic acid copolymer (nylon 9T), methylpentadiamine and terephthalic acid copolymer (Nylon M5T), polyamide resins such as a copolymer of decamethylenediamine and terephthalic acid (nylon 10T).

  The polyamide is more preferably nylon MXD-6 or nylon 9T, more preferably nylon 9T, and more preferably an intrinsic viscosity [η] (measured in concentrated sulfuric acid at 30 ° C.) of 0.80 to 1.00 dl / g.

  The glass fibers contained in the resin-impregnated fiber bundle can have a fiber diameter (single yarn diameter) of 6 to 30 μm, and the number of glass fibers in one fiber bundle is 100 to 30000, preferably 500 to 20000, The number is preferably about 1000 to 10,000.

  The resin-impregnated fiber bundle can be manufactured by a known manufacturing method using a die. For example, in addition to paragraph number 7 of JP-A-6-31350 and paragraph number 23 of JP-A-2007-176227, Japanese Patent Publication No. 6-2344 (manufacturing method and molding method of resin-coated long fiber bundle), Japanese Patent Laid-Open No. 6-114832 (fiber reinforced thermoplastic resin structure and manufacturing method thereof), Japanese Patent Laid-Open No. 6-293023 (long) Manufacturing method of fiber reinforced thermoplastic resin composition), JP-A-7-205317 (method of taking out fiber bundle and manufacturing method of long fiber reinforced resin structure), JP 7-216104A (long fiber reinforced resin structure) Manufacturing method), JP-A-7-251437 (manufacturing method and manufacturing apparatus for long fiber reinforced thermoplastic composite material), JP-A-8-118490 (black). Head die and the manufacturing method according to the long fiber-reinforced method for manufacturing a resin structure) or the like can be applied.

The content ratio of the glass fiber and the polyamide in the resin-impregnated fiber bundle used in the present invention is 40 to 70% by mass of the glass fiber, preferably 50 to 60% by mass, and the remaining proportion of the polyamide is 100% by mass in total. is there.
In addition, in order to adjust the content ratio of the glass fiber and the polyamide in the resin-impregnated fiber bundle, the polyamide can be blended in the resin composition separately from the resin-impregnated fiber bundle.

  The resin composition used in the present invention can further contain a lubricant in addition to the resin-impregnated fiber bundle. The lubricant is not added to the inside of the resin-impregnated fiber bundle, but is mixed with the resin-impregnated fiber bundle (that is, added externally). By containing the lubricant, it is possible to shorten the time for measuring the composition when it is put into the hopper during the injection molding machine, and to reduce the variation in measurement.

  Examples of the lubricant include conventional lubricants, lipids, waxes, silicone resins and the like.

  Lipids include higher fatty acids (eg, saturated C8-35 fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, montanic acid, 12-hydroxystearic acid ( Preferably saturated C12-30 fatty acids, more preferably saturated C16-22 fatty acids), unsaturated C10-35 fatty acids such as palmitooleic acid, oleic acid, erucic acid, etc.) or derivatives thereof (eg higher fatty acid salts (eg C8-35 fatty acid metal salts such as barium laurate, zinc laurate, calcium stearate, magnesium stearate, zinc stearate); higher fatty acid esters [for example, higher fatty acids such as cetyl alcohol, stearyl alcohol, oleyl alcohol and the like. Monohydric alcohol Sucrose fatty acid esters (for example, esters of sucrose such as sucrose mono to hexastearate and the higher fatty acids), glycerin fatty acid esters (for example, glycerin such as glycerin mono to tristearate and the higher Ester of fatty acid), ester of pentaerythritol and higher fatty acid, ester of diglycerin and higher fatty acid, ester of higher fatty acid and polyhydric alcohol such as ester of polyglycerin and higher fatty acid, etc.]; Higher fatty acid amides (for example, C8-35 fatty acid amides such as stearic acid amides, alkylene bis fatty acid amides such as methylene bis stearic acid amide, ethylene bis stearic acid amide, etc.) It is. These lipids can be used alone or in combination of two or more.

  Examples of the wax include aliphatic hydrocarbon wax (poly C2-4 olefin wax such as polyethylene wax, ethylene copolymer wax, polypropylene wax, paraffin wax, microcrystalline wax, etc.), vegetable or animal wax ( Carnauba wax, beeswax, shellac wax, montan wax, etc.). These waxes can be used alone or in combination of two or more.

  Examples of the silicone resin include alkyl polysiloxanes such as dimethylpolysiloxane, diethylpolysiloxane, and trifluoropropylpolysiloxane; arylpolysiloxanes such as diphenylpolysiloxane; alkylarylpolysiloxanes such as methylphenylpolysiloxane. The silicone resin may be a chain polysiloxane or a cyclic polysiloxane. These silicone resins can be used alone or in combination of two or more.

These lubricants can be used alone or in combination of two or more. Among these lubricants, a solid (or solid) lubricant is preferable at normal temperature (about 5 to 35 ° C.).
Such lubricants include lipids, in particular saturated C12-30 fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid, montanic acid, saturated C12-30 fatty acid metal salts such as calcium stearate and magnesium stearate, Preferred are glycerin mono to trisaturated C12-30 fatty acid esters such as glycerin mono to tristearic acid ester, alkylene bis saturated C12-30 fatty acid amides such as ethylene bis stearic acid amide, and particularly saturated C16 such as palmitic acid and stearic acid. Saturated C16-22 fatty acid alkaline earth metal salts such as -22 fatty acids, calcium stearate and magnesium stearate are preferably used.

  The content of the lubricant is preferably 50 to 2000 ppm, more preferably 100 to 1000 ppm with respect to the mass of the resin-impregnated fiber bundle. If it is 50 ppm or more, the effect of shortening the measurement time and the effect of improving measurement variation are sufficient, and if it is 2000 ppm or less, stable measurement can be performed.

The resin composition used in the present invention can contain various known resin additives as long as the problems of the present invention can be solved.
Known additives include thermoplastic resins other than the above-mentioned polyamides, mold release agents, antistatic agents, flame retardants, colorants, plasticizers, softeners, dispersants, stabilizers (hindered phenol antioxidants). , Phosphorus antioxidants, antioxidants such as sulfur antioxidants, UV absorbers, heat stabilizers, etc.), anti-blocking agents, crystal nucleus growth agents, fillers (particulate fillers such as silica and talc) ) And the like.

<Thin wall molding>
The thin molded article of the present invention is molded by a molding machine such as an injection molding machine using the above resin composition (resin-impregnated fiber bundle or resin-impregnated fiber bundle and other components contained as necessary). Can do.
In the present invention, at the time of injection molding, an injection mold having a pin gate is used. The size (diameter) of the pin gate is preferably 0.5 to 2.0 mm, and more preferably 0.7 to 1.5 mm. If the pin gate size is 0.5 mm or more, fiber breakage is suppressed, and the weight average fiber length in the thin molded article is prevented from being shorter than 0.5 mm. If the pin gate size is 2.0 mm or less, the gate breaks. Is good and the moldability is improved.

  The thin molded article of the present invention satisfies the following requirements (a) to (d), and preferably further satisfies the requirement (e).

<Requirement (a)>
The thickness of the thin molded body is 0.8 to 2.0 mm, and can be adjusted according to the specific application.

<Requirement (b)>
The weight average fiber length of the glass fibers in the thin molded article is 0.5 to 1.5 mm, preferably 0.5 to 1.0 mm.
In addition, the length (namely, length of glass fiber) of the resin impregnation fiber bundle which a resin composition contains is 5-15 mm, Preferably it is less than 6-12 mm. During the production of the thin molded article, the glass fiber breaks and becomes small in the process of injection molding using the resin-impregnated fiber bundle in the above range, and the range is within the requirement (b). The injection molding conditions at this time are as follows.
Injection molding machine class (30T ~ 220T)
Cylinder temperature and mold temperature: Adjust appropriately depending on the base resin (cylinder temperature 250-340 ° C, mold temperature 80-160 ° C)
High speed injection, injection primary pressure 40-200MPa, back pressure 0-10MPa, rotation speed 20-200rpm

  Moreover, even when other molding machines and other molding conditions are applied, data on the weight average fiber length in the molded body when a resin-impregnated fiber bundle having a length of 5 to 15 mm is used and the molding conditions are changed is used. By taking this, the weight average fiber length in the molded body can be easily adjusted within a predetermined range.

<Requirement (c)>
The Charpy impact strength of the thin molded article is 10 kJ or more, preferably 15 kJ or more.

<Requirement (d)>
Hygroscopic value (23 ° C / 50% RH atmosphere) with the absolute dry value of the flexural modulus of elasticity (test piece of length 80mm x width 10mm x thickness 2mm) as the standard (100%) (Saturated water absorption state) is 80% or more, preferably 90% or more.

<Requirement (e)>
The rate of dimensional change due to water absorption is 0.1% or less, preferably less than 0.1%. (Saturated water absorption state at 23 ° C./50% RH atmosphere: water absorption)

Since the thin molded article of the present invention satisfies the above requirements (a) to (d), and preferably further satisfies the requirement (e), a mobile phone, a personal digital assistant (PDA), a smartphone, a car navigation system Suitable for housing and internal chassis of electronic devices selected from game machines, compact cassettes, CD players, DVD players, electronic notebooks, electronic dictionaries, calculators, hard disk recorders, personal computers, video cameras, and digital cameras.
Among these, it is particularly suitable for a cellular phone, a personal digital assistant (PDA), a smartphone housing (a combination of an upper case and a lower case) and an internal chassis disposed inside the housing.

(polyamide)
MXD6: Reny 6002 (Mitsubishi Engineering Plastics)
PA6T-1: VESTAMID HTplus M1000 (manufactured by Daicel-Evonik)
PA6T-2: Zytel HTN501 (NC010) (manufactured by DuPont)
PA9T: Genestar N1000A (L41) (Kuraray Co., Ltd.)
(Comparative polyamide)
PA6: UBE nylon 1013B (manufactured by Ube Industries)
PA66: UBE nylon 2020B (manufactured by Ube Industries)
(Glass fiber)
GF-1: RS240QR-483 (manufactured by Nittobo) [Glass fiber roving 4000 fiber bundle Average fiber diameter 17.4 μm]
GF-2: CSX-3J-451S (manufactured by Nittobo) [Glass fiber chopped strand] (other components)
External lubricant: St-Ca (calcium stearate, SC-100 (manufactured by Sakai Chemical Industry Co., Ltd.))

(Test specimen preparation method for measuring physical properties)
Device: J-150E II manufactured by Nippon Steel Works
Screw: Screw for long fibers Screw diameter: 51mm
(1) ISO multipurpose specimen A-shaped product (thickness 2 mm)
Gate shape 20 mm wide side gate Molded product 1 is a test piece (length 80 mm × width 10 mm × thickness 2 mm) cut out from the molded product.
(2) 100-square flat plate molded product (thickness 1 mm) = molded product 2
Gate shape 10mm wide side gate

(Measuring method)
(1) Charpy impact test It conformed to ISO179 / 1eA (edgewise).
Specimen shape: length 80mm x width 10mm x thickness 2mm with notch (depth 2mm)
[ISO multipurpose test piece A-shaped product (thickness: 2 mm)] was processed using a notching machine (automatic notching machine No.189-PNCA-2 (manufactured by Yasuda Seiki Seisakusho)).

(2) Bending test (flexural modulus)
Using a molded product 1 (length 80 mm × width 10 mm × thickness 2 mm), measurement was performed at a fulcrum distance of 32 mm and a test speed of 1 mm / min.

(3) Moisture content (water absorption) and dimensional change rate (dimensional change rate due to water absorption)
After measuring the absolute quality of molded product 1 (length 80mm x width 10mm x thickness 2mm) and molded product 2 (100mm square flat plate molded product, thickness 1mm), each was immersed in water at 60 ° C for 96 hours. Soaked.
Thereafter, the molded products 1 and 2 were taken out, and after sufficiently wiping off moisture with a paper towel, the amount of molding quality was measured.
After that, the sample was left in an atmosphere of 23 ° C./50% RH to record the change in mass over time, and the state in which the mass change could not be confirmed is the saturated water absorption state in the 23 ° C./50% RH atmosphere, that is, the water absorption (hygroscopic) state. It was.
The moisture content and the dimensional change rate (change rate of the length L between the arrows shown in FIG. 1) are obtained from the following formula, and the flexural modulus (water absorption state and absolutely dry state shown in Tables 1 and 2) is expressed as “(2 ) Bending test (flexural modulus) ”.

Moisture content (%) = (Mold quality amount in water absorption (moisture absorption) state−Mold quality amount in absolutely dry state) / Mold quality amount in absolutely dry state × 100
Dimensional change rate (%) = Length L in water absorption state / Length L in absolute dry state × 100

(Weight average fiber length)
A sample of about 3 g was cut out from the molded articles 1 and 2 and heated at 650 ° C. to be ashed to take out the fibers. The weight average fiber length was determined from a part (500) of the extracted fibers. As the calculation formula, [0044] and [0045] of JP-A-2006-274061 were used.

(Measuring time measurement method)
Injection molding machine: S-2000i 100B (screw diameter 32), manufactured by FANUC Co., Ltd. Pellets were put into the hopper of an injection molding machine, and the measurement time under the following conditions was determined. The variation was confirmed for 10 shots. The measuring time (sec) was confirmed from the operation panel screen of the injection molding machine.
・ Weighing value: 40mm
・ Rotation speed: 80rpm
・ Back pressure: 3MPa
・ Cylinder temperature: 280 ℃

Example 1
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 60 mass% and a length of 9 mm was obtained.
The pellets obtained by adding 200 ppm of calcium stearate (St-Ca) as an external lubricant were injection molded (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)), and test pieces for each measurement were prepared. Produced.

Example 2
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 60 mass% and a length of 9 mm was obtained.
The obtained pellets were directly injection-molded (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)) to prepare test pieces for measuring the respective physical properties.

Example 3
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 6 mm was obtained.
The pellets obtained by adding 200 ppm of calcium stearate (St-Ca) as an external lubricant were injection molded (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)), and test pieces for each measurement were prepared. Produced.

Example 4
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 12 mm was obtained.
Test pellets for measuring the physical properties of the pellets obtained by injection molding (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)) with calcium stearate (St-Ca) 200 ppm added as an external lubricant. Was made.

Example 5
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 40 mass% and a length of 9 mm was obtained.
Test pellets for measuring the physical properties of the pellets obtained by injection molding (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)) with calcium stearate (St-Ca) 200 ppm added as an external lubricant. Was made.

Example 6
PA6T-1 as a thermoplastic resin is supplied in a molten state (340 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. Then, the glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 9 mm was obtained.
Test pellets for measuring physical properties of the obtained pellets obtained by adding 200 ppm calcium stearate (St-Ca) as an external lubricant to injection molding (cylinder temperature 330 ° C., mold temperature 140 ° C. (actual measurement)) Was made.

Example 7
PA6T-2 as a thermoplastic resin is supplied in a molten state (340 ° C.) from an extruder connected to the crosshead while drawing the glass fiber roving (GF-1) through a crosshead that has a continuous fiber passage processed into a wave shape. Then, the glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 9 mm was obtained.
Test pellets for measuring physical properties of the obtained pellets obtained by adding 200 ppm calcium stearate (St-Ca) as an external lubricant to injection molding (cylinder temperature 330 ° C., mold temperature 140 ° C. (actual measurement)) Was made.

Example 8
PA9T as a thermoplastic resin is supplied in a molten state (340 ° C.) from an extruder connected to the crosshead while drawing the glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 60 mass% and a length of 9 mm was obtained.
Test pellets for measuring physical properties of the obtained pellets obtained by adding 200 ppm calcium stearate (St-Ca) as an external lubricant to injection molding (cylinder temperature 330 ° C., mold temperature 140 ° C. (actual measurement)) Was made.

Example 9
PA9T as a thermoplastic resin is supplied in a molten state (340 ° C.) from an extruder connected to the crosshead while drawing the glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 9 mm was obtained.
Test pellets for measuring physical properties of the obtained pellets obtained by adding 200 ppm calcium stearate (St-Ca) as an external lubricant to injection molding (cylinder temperature 330 ° C., mold temperature 140 ° C. (actual measurement)) Was made.

Comparative Example 1
As a thermoplastic resin, 50% by mass of MXD6 and 50% by mass of glass fiber chopped strand (GF-2) were mixed in a tumbler blender, and then melt-kneaded in an extruder (270 ° C.) to obtain a pellet-shaped resin composition. .
The obtained pellets were injection-molded (cylinder temperature 270 ° C., mold temperature 130 ° C. (actual measurement)) to prepare test pieces for each measurement.

Comparative Example 2
As a thermoplastic resin, 50% by mass of PA9T and 50% by mass of glass fiber chopped strand (GF-2) were mixed in a tumbler blender, and then melt-kneaded in an extruder (320 ° C.) to obtain a pellet-shaped resin composition. .
The obtained pellets were injection-molded (cylinder temperature 330 ° C., mold temperature 140 ° C. (actual measurement)) to produce test pieces for each measurement.

Comparative Example 3
PA66 is supplied in a molten state (320 ° C.) from an extruder connected to the crosshead as a thermoplastic resin while pulling glass fiber roving (GF-1) through a crosshead processed into a corrugated continuous fiber passage. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 60 mass% and a length of 9 mm was obtained.
The pellets obtained by adding 200 ppm of calcium stearate (St-Ca) as an external lubricant were injection molded (cylinder temperature 300 ° C., mold temperature 100 ° C. (actual measurement)), and test pieces for each measurement were prepared. Produced.

Comparative Example 4
While drawing glass fiber roving (GF-1) through a crosshead processed into a wave-like continuous fiber passage, PA6 is fed in a molten state (290 ° C) from an extruder connected to the crosshead as a thermoplastic resin. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 60 mass% and a length of 9 mm was obtained.
Test pellets for measuring each physical property were prepared by injection molding (cylinder temperature 280 ° C., mold temperature 100 ° C. (actual measurement)) obtained by adding 200 ppm calcium stearate (St-Ca) as an external lubricant to the obtained pellets. did.

Comparative Example 5
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
Then, it was taken as a strand through a shaping die, cut after cooling, and a pellet (resin-impregnated fiber bundle) having a glass fiber content of 50 mass% and a length of 18 mm was obtained.
I tried injection molding (cylinder temperature 280 ° C., mold temperature 130 ° C. (actual measurement)) with the addition of calcium stearate (St-Ca) 200 ppm as an external lubricant to the obtained pellets, but the pellets bite into the screw. Somehow, injection molding was not possible.

Comparative Example 6
MXD6 as a thermoplastic resin is fed in a molten state (290 ° C.) from an extruder connected to the crosshead while pulling glass fiber roving (GF-1) through a crosshead that is formed by corrugated continuous fiber passages. The glass fiber was impregnated.
After that, it was taken out as a strand through a shaping die, cut after cooling, and an attempt was made to produce a pellet with a glass fiber content of 50% by mass and a length of 4 mm, but the pellet was cracked and could not be obtained. It was.

  From the comparison between Example 3 (MXD6 + GF-1) in Table 1 and Comparative Example 1 (MXD6 + GF-2) in Table 2, the flexural modulus and Charpy depend on the weight average fiber length of the glass fiber contained in the molded product 1. It was confirmed that there was a difference in impact strength. Moreover, it was confirmed that the difference in the dimensional change rate was caused by the size of the weight average fiber length of the glass fibers contained in the molded product 2.

  From the comparison between Example 9 (PA9T + GF-1) in Table 1 and Comparative Example 2 (PA9T + GF-2) in Table 2, the flexural modulus and Charpy depend on the weight average fiber length of the glass fiber contained in the molded product 1. It was confirmed that there was a difference in impact strength. Moreover, it was confirmed that the difference in the dimensional change rate was caused by the size of the weight average fiber length of the glass fibers contained in the molded product 2.

  Like Example 3 (paragraph number 67) of patent document 2, when it is going to make the weight average fiber length of the glass fiber in a molded article into 3-5 mm, rather than the pellet (length 18mm) of the above-mentioned comparative example 5. Since it is necessary to use a long pellet, a thin molded article cannot be manufactured.

Claims (4)

After long glass fibers are bundled in a state of being aligned in the length direction, the glass long fibers bundle is impregnated and integrated in a melted state, and then cut to a length of 5 to 15 mm, nigrosine and / or its and a resin-impregnated fiber bundle not containing derivative, the saw including a lubricant which added separately to the resin-impregnated fiber bundle, a thin molded article obtained from nigrosine and / or resin composition that does not contain a derivative thereof,
The polyamide in the resin-impregnated fiber bundle is selected from nylon MXD6, nylon 6T and nylon 9T having an intrinsic viscosity [η] (measured in concentrated sulfuric acid at 30 ° C.) of 0.80 to 1.00 dl / g ,
A thin molded article having a glass fiber content in the resin-impregnated fiber bundle of 40 to 70% by mass and satisfying the following requirements (a) to (d).
(A) The thickness of the thin molded body is 0.8 to 2.0 mm.
(B) The weight average fiber length of the glass fibers in the thin molded body is 0.5 to 1.0 mm.
(C) Charpy impact strength of the thin-walled molded product is 10 kJ or more. (D) The absolute dry value of the bending elastic modulus (length 80 mm × width 10 mm × thickness 2 mm test piece) of the thin-walled molded product is used as the standard (100%). When the moisture absorption value is 80% or more The thin-walled molded product according to claim 1, further satisfying the requirement that (e) the dimensional change rate due to water absorption is 0.1% or less (saturated water absorption state in an atmosphere of 23 ° C / 50% RH). The thin molded body is for electronic device housings,
Electronic equipment housing is mobile phone, personal digital assistant (PDA), smart phone, car navigation, game machine, compact cassette, CD player, DVD player, electronic notebook, electronic dictionary, calculator, hard disk recorder, personal computer, video camera, claim 1 or 2 thin molded article wherein the housing of an electronic device selected from a digital camera. A housing or the chassis of the thin molded product is an electronic device, the housing or the chassis of the electronic device, a cellular phone, a personal digital assistant (PDA), a thin Claim 1 or 2, wherein the housing or the chassis of the smartphone Molded body.

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