JPH11320737A - Fiber reinforced thermoplastic molding material and housing for electronic/electric equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thin molding material which is high in strength and rigidity and excellent in electromagnetic wave shielding, appearance, and design by a method in which a reinforcing fiber fabric is impregnated with a thermoplastic resin in order to have specified values or above of flexural modulus of elasticity, flexural strength, and impact absorption energy. SOLUTION: In a fiber reinforced thermoplastic resin material, a reinforcing fiber fabric is impregnated with a thermoplastic resin. Its flexural modulus of elasticity is 15 GPa or above; flexural strength is 30 MPa or above; impact absorption energy is 15 J/mm. In addition, the reinforcing fiber volume ratio is 30-60%, and the warp and weft numbers of the fabric are 0.5-10/inch. In this way, the fiber reinforced thermoplastic resin molding material is excellent in strength, rigidity, and impact resistance as compared with an injection molded article, and can control surface defects such as pits and obtain a good appearance with a fold passed through.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for molding a fiber-reinforced thermoplastic resin, a housing material suitable for various portable electronic devices such as a personal computer and a word processor, and a mobile terminal such as a mobile phone, and a housing thereof. About.

[0002]

2. Description of the Related Art In the age of information technology, with the advent of the multimedia network era, various portable electronic devices and portable terminals, which are portable information and communication devices, have been reduced in size and size to enhance portability. For this reason, weight reduction has become the most important proposition (Nikkei Mechanical, 1996, No. 477,
pp 70-83). Under such circumstances, there is a demand for a housing material that can realize rigidity and impact resistance to protect internal components even with a thickness of about 1 mm, can be processed to be thin, and can be recycled. Under such circumstances, the following are cited as conventional techniques.

For example, Japanese Patent Publication No. 5-58371 discloses a carbon fiber reinforced thermosetting resin composite material in which carbon fibers having a fiber length of 10 to 100 mm are randomly oriented in a plane. , CFRTS) are shown. This molded article has the following disadvantages.

[0004] That is, the above-mentioned molded article has a drawback that the thermosetting resin flows and cures in the mold, so that the curing time is as long as 3 minutes or more and the molding cycle is long, so that the production cost is increased. Another problem is that it is difficult to recycle the molded product because the thermosetting resin is used as the matrix. In some cases, defective moldings and scraps are collected, heated to 400 to 600 ° C., for example, a thermosetting resin such as a phenolic resin is separated from carbon fibers, and the carbon fibers are reused. The vaporized thermosetting resin is
There is also a measure of collecting the gas or liquid, burning it to eliminate toxicity, and then releasing it to the atmosphere (Nikkei Mechanical, 1996, No. 477, pp. 70-83). However, such a recycling method as described above has a disadvantage that much energy is required for separating the carbon fiber and the thermosetting resin, and the recycling efficiency is poor.

[0005] Therefore, as a measure for reducing the production cost, for example, polycarbonate or AB, which is easy to mold, is used.
Injection molding material (Short Carbon Fiber Rei) in which a thermoplastic resin such as S or these alloys is reinforced with carbon fiber.
nforced Thermoplastic Composites; SCFRT
P). In this case, when performing injection molding, the carbon fiber is cut into a length of 1 mm or less when passing through the cylinder or gate of the injection molding machine, or the content of the fiber cannot be increased. Therefore, the molded article has a drawback that the reinforcing efficiency is low in spite of using expensive carbon fiber, and the electromagnetic shielding property is also reduced.

Further, in order to compensate for the decrease in strength and rigidity, it is necessary to provide ribs for imparting rigidity to the molded product, so that it is difficult to make the molded product thinner, and it has become difficult to satisfy the recent demand for lighter and thinner products. ing. And, since the length of the carbon fiber in the molded article is already 1 mm or less, there is little merit when used for recycling, and there is no disposal method other than incineration.

In order to overcome the above-mentioned drawbacks such as CFRTS and SCFRTP, Japanese Patent Application Laid-Open No. H8-24405 discloses that carbon fibers having a length of 3 to 100 mm arranged in random directions in a plane parallel to the plate surface. Material for carbon fiber strong heating thermoplastic resin using carbon and polyphenylene sulfide (hereinafter abbreviated as PPS) (Carbon Mat Reinfoece
d Thermoplastic; hereinafter referred to as CMT).

[0008] The molding material is preheated, charged into a mold maintained at a certain temperature, pressed, cooled, and solidified to be molded (stamping molding), so that the fiber is hardly broken. . It is stated that a molded article molded by this material and molding method has high strength and rigidity, excellent electromagnetic wave shielding characteristics, and a thin molded article because long reinforcing fibers are mixed in the resin.

The molding material is obtained by superposing a PPS film on a defibrated mat of a reinforcing fiber or a chopped strand mat, and heating and pressurizing the PPS film to perform impregnation.
The PPS-coated carbon fiber obtained by coating the carbon fiber bundle with PPS is preheated, processed into a tape shape by passing through a pressure roll, cut into a tape, scattered in a mold, and compression molded. . However,
It is very difficult to impregnate defibrated mats and chopped strand mats with PPS, which is a thermoplastic resin having high viscosity, and often impregnation of the resin between the reinforcing fibers is insufficient. . Insufficient resin impregnation causes defects such as cavities, pinholes and pock-like defects on the surface of the molded product, which not only does not withstand the appearance of the housing, but also reduces the strength. There is.

[0010] Furthermore, the above-mentioned production method has a drawback that the fiber pattern may remain due to the reinforcing fibers floating on the surface of the molded article, which impairs the appearance of the molded article. In order to hide such defects that impair the surface properties, it is necessary to apply urethane coating on the molded product surface, which not only increases the cost but also requires the paint to be peeled off when recycling, which raises the recycling cost. Will be invited.

In recent years, there has been seen a case in which magnesium, which is the lightest metal that can be used as a structural material, is injection molded (thixomolded). Such a case has excellent features that it is lightweight, has high rigidity, has good electromagnetic wave shielding properties and recyclability, can be thinned, and has high productivity.

However, since the case using magnesium is made of metal, it has a drawback that the vibration damping rate is low and the vibration damping property is lacking. Personal computers have a built-in rotating hard disk, etc., so if the housing has poor damping properties, such vibrations of the driving parts will become unpleasant vibrations and will be transmitted to the hands of the person who inputs directly. Occurs.

Further, unlike resin parts, since the elastic modulus is too high, a technique such as snap-on cannot be used for connecting parts, and it is necessary to use a lot of screws. Excessive use of screwing not only causes an increase in the number of assembly steps, but also has a disadvantage that it makes it difficult to disassemble a device whose service life has expired, thereby increasing the recycling cost.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional housing, and to provide a thin, high-strength, high-rigidity, excellent electromagnetic-wave shielding property, and excellent design in appearance. And a housing using the same.

[0015]

Means for Solving the Problems In order to achieve the above object, the present inventors have made intensive studies and found that reinforcing fibers in the form of a woven fabric are used and have a physical property of a certain level or more. The inventors have found that molding materials are useful, and have reached the present invention. That is, the present invention has the following configuration. (1) A fiber-reinforced thermoplastic resin material obtained by impregnating a reinforcing fiber in the form of a woven fabric with a thermoplastic resin, having a flexural modulus of 15 GPa or more, a flexural strength of 30 MPa or more, and a shock absorption energy of 15 J / mm or more. A material for molding a fiber-reinforced thermoplastic resin, characterized in that: (2) The material for molding a fiber-reinforced thermoplastic resin according to (1), wherein the volume content of the reinforcing fibers is 30 to 60%. (3) The number of driven warp yarns and weft yarns is 0.5
The material for molding a fiber-reinforced thermoplastic resin according to (1) or (2), wherein the number is 10 to 10 / inch. (4) The flatness of the reinforcing fiber bundle is 5 or more (1) to
The material for molding a fiber-reinforced thermoplastic resin according to any of (3). (5) The crimp rate of the reinforcing fiber is 0.2 or less (1)
The material for molding a fiber-reinforced thermoplastic resin according to any one of (1) to (4). (6) The luminance distribution measured using a three-dimensional variable angle photometer is 1
The material for molding a fiber-reinforced thermoplastic resin according to any one of (1) to (5), which changes at a cycle of 80 °. (7) Any one of (1) to (6), wherein the brightness in the fiber axis direction of the warp or weft measured using a brightness meter is a waveform on a pulse having a period of 0.1 inch or 2 inches. The material for molding a fiber-reinforced thermoplastic resin according to item 1. (8) The material for molding a fiber-reinforced thermoplastic resin according to any one of (1) to (7), wherein one or more reinforcing fiber fabrics are impregnated with a thermoplastic resin. (9) The fiber-reinforced thermoplastic according to any one of (1) to (7), obtained by heating, melting, impregnating, cooling and solidifying a fabric woven from a mixed yarn of a thermoplastic resin and a reinforcing fiber. Materials for resin molding. (10) The fiber-reinforced thermoplastic resin according to any one of (1) to (7), obtained by heating, melting, impregnating, cooling, and solidifying a fabric woven from a reinforcing fiber bundle impregnated with a thermoplastic resin. Molding materials. (11) A housing material comprising the fiber-reinforced thermoplastic resin molding material according to any one of (1) to (10). (12) A housing for electronic / electric equipment, wherein the housing material according to (11) is partially or entirely used.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fiber-reinforced thermoplastic resin molding material (hereinafter referred to as FRTP) of the present invention preferably has a volume content of reinforcing fibers (hereinafter referred to as Vf) of 30 to 60%. When the Vf of the reinforcing fibers is less than 30%, the strength and rigidity are insufficient, and when the impact force is applied, the amount of the reinforcing fibers against the impact strength is small, so that the impact resistance is poor. If the Vf of the reinforcing fiber exceeds 60%, impregnation of the resin tends to be poor, and there is a possibility that the strength is reduced due to insufficient impregnation. Since the reinforcing form is a woven fabric and continuous fibers are used, the strength and rigidity of the reinforcing fibers can be sufficiently utilized.

It is preferable to use a woven fabric having a warp and a weft of 0.5 to 10 yarns / inch for each of the woven fabrics used as the reinforcing fibers. If it is less than 0.5 fibers / inch, weaving is difficult due to the wide width of the reinforcing fiber bundle. On the other hand, if it is larger than 10 / inch, the straightness of the reinforcing fiber is inferior, the thickness of the woven fabric is large, and it is difficult to obtain an optimal thin thickness for the housing.

The flatness and the crimp rate in FRTP are as follows. A small piece cut out of FRTP has a length of 25.4 mm or more, and a cross section perpendicular to any fiber axis of the warp yarn is polished. Can be obtained on the basis of the result obtained by magnifying 50 times or more.
FIG. 1 shows an example of the cross-sectional observation photograph.

The flatness in the present invention refers to the aspect ratio (long (a)) in a cross section perpendicular to the fiber axis of a fiber bundle constituting a woven fabric as schematically shown in FIG. ) / Short (b)). The flatness in the present invention is preferably 5 or more. If the number of reinforcing fiber bundles is less than 5, the accumulation of thermoplastic resin (resin-rich portion) between the fiber bundles is likely to occur, which may be a defect, resulting in a decrease in strength.

Similarly, the crimp ratio in the present invention is:
It is a value defined by the ratio of thickness (d) / pitch (c) when the warp or the weft as shown in the schematic diagram of FIG. 2 exceeds the weft or the warp. The crimp rate in the present invention is preferably 0.2 or less. If the crimp ratio of the reinforcing fiber bundle is larger than 0.2, the swelling of the reinforcing fiber bundle becomes large and the straightness is reduced, so that play of the reinforcing fiber occurs in the molded product, and the rigidity is reduced. For the same reason, when an impact force is applied, the contribution of the fiber strength is reduced, and the impact absorption energy may be reduced.

In order to exhibit a characteristic appearance, for example, a three-dimensional variable angle photometer (GP-200 manufactured by Murakami Color Research Laboratory)
It is preferable that the luminance measured by the method described above is periodically changed. For example, using a personal image processing system (Pierce Co., Ltd., PIAS LA-500) or the like, the surface of the FRTP is photographed by a CCD, and the fiber in the image obtained by image processing is obtained. Preferably, the brightness in the axial direction changes in a pulsed manner at a period related to the distance between the fiber bundles.

Further, the luminance measured by two-dimensional reflected light distribution measurement using a three-dimensional variable-angle altimeter changes at a cycle of 180 ° as shown in FIG. Surface characteristics with various aspects depending on the viewing direction. It is supposed that such an aspect appears due to optical anisotropy existing in the fiber axis direction and the circumferential direction of the reinforcing fiber.

The characteristic appearance as shown in FIG. 6 can be obtained by changing the brightness of the warp or weft in the fiber axis direction at a constant period as shown in FIG. It is considered that such an appearance is obtained by excellent straightness of each reinforcing fiber (monofilament) constituting the reinforcing fiber bundle and high parallelism between the fibers,
It is considered that the higher these values, the sharper the rise of the pulse and the larger the difference between the upper and lower peaks.

In order to obtain the FRTP of the present invention, at least one or more reinforced fiber woven fabrics are impregnated with a thermoplastic resin, or a woven fabric of a mixed yarn of the thermoplastic resin and the reinforced fibers is heated, melted and impregnated. It can be obtained by using a cloth which is cooled, solidified, or woven with a reinforcing fiber bundle impregnated with a thermoplastic resin.

In the FRTP of the present invention, the reinforcing fibers include, for example, glass fibers, carbon fibers, silicon carbide fibers,
Inorganic fiber such as alumina fiber and metal wire, metal fiber, aramid fiber, high molecular weight polyethylene fiber, PBO
Organic fibers such as fibers can be used. Among them, when used as a housing, it is desirable to use carbon fiber or metal fiber from the viewpoint of electromagnetic wave shielding properties.
Further, from the viewpoint of weight reduction and the viewpoint of having the above-described optical anisotropy, it is more preferable to use carbon fibers.

As the resin to be combined with the reinforcing fiber,
Thermosetting resins and thermoplastic resins are exemplified. From the viewpoint of recycling, a thermoplastic resin is preferable, and from the viewpoint of cost, an olefin resin such as polypropylene and a polyamide resin such as nylon are preferable. When flame retardancy is particularly important, it is preferable to use a flame-retardant resin such as polyphenylene sulfide, and when impact resistance is important, it is preferable to use polycarbonate or polymethyl methacrylate.
If necessary, there is no problem even if an additive or the like is added to these resins for the purpose of improving weather resistance, preventing deterioration due to ultraviolet rays, and improving flame retardancy.

Further, using the above-mentioned material, the above-mentioned FRT
As a means for obtaining P, for example, at least one or more reinforcing fiber woven fabric and a thermoplastic resin on a sheet are heated, pressed, melted and impregnated in a mold, cooled and solidified to form a plate-like FRTP.
Can be obtained. In this case, it can be obtained by cooling and solidifying the mold to normal temperature while maintaining the temperature higher than the melting point of the resin.

Further, a cloth woven from a blended yarn obtained by previously blending a thermoplastic resin fiber and a reinforcing fiber is placed in a mold heated to a temperature higher than the melting point of the thermoplastic resin fiber by 2.5 mm.
It can be obtained by heating, pressurizing, melting, impregnating, cooling, and solidifying while applying a pressure of up to 5.0 MPa. More desirably, after unwound so as not to cause untwisting, the opened reinforcing fiber is passed through a die filled with a thermoplastic resin under pressure, and a tape-like shape impregnated with the taken-out thermoplastic resin is used. A reinforcing fiber bundle is prepared, and the woven fabric is heated and heated in a mold heated to a temperature higher than the melting point of the thermoplastic resin while maintaining a low pressure of 0.2 to 2.5 MPa. It can be obtained by using a material that has been pressed, melted, impregnated, cooled and solidified. The FRTP thus obtained can be obtained, in particular, with excellent straightness of the reinforcing fiber and excellent parallelism of the monofilament.

As a means for obtaining the FRTP, there is no problem even if, for example, a double belt press or an intermittent double belt press using a press is used in addition to the method using a mold. Further, for the purpose of preventing slippage, it is more preferable that the surface is provided with fine irregularities, graining, or the like.

The FRTP of the present invention has a flexural modulus of 15 GP.
a, the bending strength is 30 MPa or more, and the impact absorption energy is 15 J / mm or more. The FRTP of the present invention has rigidity and can provide a housing excellent in impact resistance. Flexural modulus less than 15 GPa, flexural strength less than 300 MPa, or shock absorption energy of 1
If it is less than 5 J / mm, many ribs are required due to low rigidity, and it is difficult to reduce the thickness, and when a compressive load is applied to the housing, the deformation is large. The plate may be deformed and destroyed. And when it hits the corner of the desk again, it is fragile and cannot protect the inside.

The FRT of the present invention having the above features
P is particularly useful for use as a housing for electronic and electrical equipment. Here, the electronic and electric devices include, for example, desktop computers, laptop computers, notebook computers, sub-notebook computers, word processors, personal digital assistants, mobile phones, portable computer peripheral devices (hard disk,
Removable disk, printer, LCD monitor),
Examples include a liquid crystal television, a digital camera, a digital video, a portable cassette tape recorder, a portable mini-disc player, a portable compact disc player, etc., and broadly refer to electronic devices in general.

[0032]

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not particularly limited by the examples. In the examples, the flexural modulus and flexural strength are JIS K 7055, and the impact absorption energy is A
According to STM D3029, the luminance distribution can be determined, for example, by referring to “Recent glossiness measurement method” (Masao Sawaji, Senshou Kogyo, Vol.
18, No. 11, p46-55) and the like.

Example 1 A carbon fiber roving was opened and passed through a die filled with polypropylene at 220 ° C., a width of 10 mm, a thickness of 0.1 mm, and a fiber volume content of 50%.
Was obtained. Weaving this molding material,
Three layers of this woven fabric are laminated, 220 ° C., 10 kgf / cm ²
The mixture was heated and cooled under heat and pressure for 5 minutes to obtain a fiber reinforced thermoplastic resin flat plate (implantation number: 2.25 lines / inch, flatness: 87.5, crimp rate: 0.0085). FIG. 7 shows the results of cross-sectional observation of this flat plate, and Table 1 shows the physical properties and evaluation results. FIG. 8 shows an example of a computer housing using this material.

Example 2 Three layers of a mixed fiber woven fabric of carbon fibers and polyamide 6 were laminated, and were heated at 250 ° C. and 20 kgf / cm ^2.
The mixture was heated for 10 minutes under heating and pressurization, and cooled to obtain a fiber-reinforced thermoplastic resin flat plate (10 pieces / inch, flatness 5.4, crimp rate 0.0595). Table 1 also shows the physical properties and evaluation results.

[Example 3] Glass fiber roving was added to 22
Pass through a die filled with 0 ° C polypropylene, width 1
0mm, 0.1mm thick, 50% fiber volume content
A molding material in the form of a loop was obtained. The woven fabric of this molding material
Two layers laminated, 220 ° C, 10kgf / cm ^TwoHeating and heating
After heating under pressure for 5 minutes, cool and heat fiber reinforced thermoplastic
Composite material flat plate (number of driving 2.25 lines / inch, flat
A flatness of 75 and a crimp rate of 0.0104 were obtained. If physical properties
Table 1 shows the evaluation results.

[Comparative Example 1] 40 shots / inc
h and a stack of glass fiber fabric (13 layers) and polyamide 6 film alternately at 250 ° C. and 15 kgf
/ Cm ² for 10 minutes under heating / pressurization and cooling to obtain a fiber-reinforced thermoplastic resin composite material flat plate. The flatness of this flat plate was 6.39, and the crimp ratio was 0.24. Table 1 shows the physical properties and evaluation results of this flat plate.

[Comparative Example 2] A commercially available stampable sheet (glass fiber / polypropylene, Vf 19%) was used for 220
℃ 5kgf / cm ² under heating and pressure for 1 minute,
Upon cooling, a fiber reinforced thermoplastic resin composite plate was obtained. Table 1 shows the results.

Comparative Example 3 A commercially available injection molding material of carbon fiber-added polyamide 6 was injection molded to obtain a fiber-reinforced thermoplastic resin composite plate. Table 1 shows the evaluation results.

[0039]

[Table 1]

[0040]

As described above, the fiber-reinforced thermoplastic resin molding material of the present invention is superior in strength and rigidity to injection molded articles, and has good impact resistance. In addition, unsightly flow patterns (traces of flow) generated by stampable sheets and sheet molding compounds,
It is possible to suppress surface defects such as a fiber pattern (right side of fiber) and pock, and to obtain a good appearance through a fold. Furthermore, since such a good appearance is obtained, there is no need for painting, and since it is a thermoplastic resin composite material using continuous reinforcing fibers in recycling, it is pelletized as it is, and as a material for injection molding It can be reused, and it is easy to reduce recycling costs and energy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross-section observer immersion in an example of the fiber-reinforced thermoplastic resin material of the present invention.

FIG. 2 is a schematic diagram relating to a cross-sectional observation photograph of an example of the fiber-reinforced thermoplastic resin molding material of the present invention.

FIG. 3 is a view showing a luminance distribution that changes in a cycle of 180 for an example of the fiber-reinforced thermoplastic resin material of the present invention.

FIG. 4 is a view showing that the appearance of an example of the fiber-reinforced thermoplastic resin molding material of the present invention changes depending on the incident angle of light.

FIG. 5 is a diagram showing a brightness distribution in the fiber axis direction for an example of the fiber-reinforced thermoplastic resin molding material of the present invention.

FIG. 6 is a diagram showing surface observer immersion for an example of the fiber-reinforced thermoplastic resin molding material of the present invention.

FIG. 7 is a view showing a cross-sectional observation photograph of the fiber-reinforced thermoplastic resin flat plate obtained in Example 1 of the present invention.

FIG. 8 is a view showing an observation photograph of a computer housing using the thermoplastic resin flat plate obtained in Example 1 of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 101: 12 105: 08 B29L 31:34

Claims (12)

[Claims] 1. A fiber-reinforced thermoplastic resin material in which a thermoplastic resin is impregnated into a reinforcing fiber in the form of a woven fabric, and has a flexural modulus of 15 GPa or more, a flexural strength of 30 MPa or more, and a shock absorption energy of 15 J / mm or more. A material for molding a fiber-reinforced thermoplastic resin, characterized in that: 2. The fiber-reinforced thermoplastic resin molding material according to claim 1, wherein the volume content of the reinforcing fibers is 30 to 60%. 3. The fiber-reinforced thermoplastic resin molding material according to claim 1, wherein the number of warp yarns and the number of weft yarns is 0.5 to 10 yarns / inch. 4. The material for molding a fiber-reinforced thermoplastic resin according to claim 1, wherein the flatness of the reinforcing fiber immediately is 5 or more. 5. The fiber-reinforced thermoplastic resin molding material according to claim 1, wherein the crimp ratio of the reinforcing fibers is 0.2 or less. 6. The fiber-reinforced thermoplastic resin molding material according to claim 1, wherein the luminance distribution measured with a three-dimensional variable angle photometer changes with a period of 180 °. 7. The brightness of a warp or a weft in a fiber axis direction measured using a brightness meter is 0.1 inch or 2 inch.
The fiber-reinforced thermoplastic resin molding material according to any one of claims 1 to 6, wherein the material has a pulse-like waveform having a period of ch. 8. The material for molding a fiber-reinforced thermoplastic resin according to claim 1, wherein at least one reinforcing fiber fabric is impregnated with a thermoplastic resin. 9. The fiber-reinforced thermoplastic according to claim 1, which is obtained by heating, melting, impregnating, cooling and solidifying a fabric woven from a mixed yarn of a thermoplastic resin and a reinforcing fiber. Materials for resin molding. 10. The fiber-reinforced thermoplastic resin according to claim 1, which is obtained by heating, melting, impregnating, cooling and solidifying a fabric woven from a reinforcing fiber bundle impregnated with a thermoplastic resin. Molding materials. 11. A housing material comprising the fiber-reinforced thermoplastic resin molding material according to claim 1. Description: 12. A housing for an electronic / electric device, wherein the housing material according to claim 11 is partially or wholly used.