JP2002001209A - Method for coating resin molding and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method which forms a coating film which has strong adhesive force and is difficult to be peeled off on a molding of a liquid crystal polymer, satisfies good exterior decoration and functions, and is high in work efficiency and a coated article. SOLUTION: A metal plating film 4 is formed on the outer surface 1b of a housing 1 of the liquid crystal polymer, a circuit pattern 3 of a metal plating film is formed on the inner surface 1a of the housing 1, and the coating film 7 is formed by coating the film 4 of the outer surface 1b by a spray method, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coating a resin molded article and a coated article.

[0002]

2. Description of the Related Art In recent years, housings for electronic parts, especially memory stick housings, have been required to be thinner. In order to improve rigidity and mechanical strength and to secure thin-walled formability,
Liquid crystal polyester has come to be used as a material for the housing.

[0003] The liquid crystal polyester has various excellent properties in terms of physical properties such as heat resistance, mechanical properties, and electrical properties.

[0004]

However, on the other hand, on the other hand, since the liquid crystal polyester is inert and has good solvent resistance, a coloring agent is added to the pellets or a coating is applied to the surface of the molded article. Difficult to apply.
In particular, in the case of the latter, there is a problem that even if the coating can be performed, the adhesion of the coating film is weak and the coating film is easily peeled.

[0005] As a result, many of the coated molded articles are unsuitable as exterior parts and have low commercial value. As described above, since it is impossible to apply the liquid crystal polyester with only one coat of the top coat, it is necessary to increase the number of steps such as etching the surface and combining the primer and the top coat. Was. For example, when a chlorinated polyolefin / acrylic system is used as a primer and an acrylic / urethane system is applied as a top coating, the adhesion of the coating is improved, but the primer is a halogen compound and is not suitable for use from an environmental point of view.

SUMMARY OF THE INVENTION The present invention has been made to improve the above circumstances, and an object of the present invention is to obtain a coating film having a strong adhesive force by reducing the number of steps, and to provide an exterior and a coating especially for electronic products. It is an object of the present invention to provide a method for coating a resin molded article which satisfies both functions, has a high working efficiency and does not adversely affect the environment, and a coated product.

[0007]

That is, in the method of coating a resin molded article of the present invention, a metal film (particularly a metal plating film) is formed on a molded article made of a liquid crystal polymer such as liquid crystal polyester, and the surface of the metal film is formed. It is characterized in that it is painted.

[0008] The coated article of the present invention is characterized in that a metal film (particularly a metal plating film) is formed on the surface of a molded product made of a liquid crystal polymer such as liquid crystal polyester, and that the metal film is further coated. Features.

According to the present invention, a metal film is formed on a molded body made of a liquid crystal polymer, and the surface of the metal film is coated. Therefore, the liquid crystal polymer molding having excellent solvent resistance but poor paint adhesion is obtained. To the body, through a metal film with good adhesion to the paint, with only one coat, without the need for etching treatment, primer and top coating, that is, with a small number of man-hours, the adhesion is large, A difficult coating film can be formed, and a coated article having this coating film can be efficiently obtained.

[0010] Particularly, for electronic and electrical products, by leaving a non-painted portion for a wiring circuit when coating a resin molded body such as a housing, the painted portion is used for improving the appearance, and the unpainted portion is used for improving the appearance. It is possible to provide a high-product-value resin molded product that integrates functions and appearance and function with high efficiency (by reducing man-hours and assembly parts).

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, it is desirable that the liquid crystal polymer is a liquid crystal polyester having excellent fluidity during molding. FIG. 4 shows the properties (continuous use temperature, thermal expansion coefficient, water absorption) of the liquid crystal polymer (LCP) as compared with those of other polymers, all of which show excellent physical properties. This makes it possible to form an ultra-thin housing having an average thickness of 0.3 mm or less by taking advantage of high fluidity, high rigidity, and the like, so that the device can be reduced in size and thickness.

[0012] It is preferable that the molded body is a housing of an electronic device, and the paint is applied to the appearance surface of the housing.

The housing is not limited to a particular shape, but is usually a memory stick housing or a mobile phone housing.

In the present invention, a metal plating film is formed on an inner surface and an outer surface of the casing made of the liquid crystal polymer, and the metal plating film on the inner surface is used for a wiring circuit. It is preferable to apply the above-mentioned coating. In this manner, the wiring circuit (further, the connector) and the housing (including the exterior) can be integrated, the number of parts can be reduced, the number of assembly steps can be reduced, and the cost can be reduced.

Further, when the coating method of the present invention is carried out, the wiring circuit is provided on the inner surface of the housing by MID (Mold int).
erconnect device) forming directly by a forming method;
Preferably, the step of forming the metal plating film on the outer surface of the housing is performed simultaneously. That is, an electronic circuit is formed by metal plating on the inner surface of a liquid crystal polymer housing by the MID forming method, and at the same time, metal plating is also performed on the front surface on the exterior surface side. It is good to coat with a coat.

[0016] For electronic and electrical products, it is preferable to mount an electronic component on the wiring circuit on the inner surface of the housing.

Next, the present invention will be described in detail based on preferred embodiments with reference to the drawings as appropriate.

FIG. 1, FIG. 2 and FIG. 3 show a flow of a preferred coating method of the present invention. This flow comprises steps from (A) to (J).

Step (A): Step 1 shows a case for a memory stick (see also FIG. 6), and this case 1 is made of a liquid crystal polymer such as liquid crystal polyester, and is mainly manufactured by injection molding. FIG. 5 shows an injection molding machine 20 used for this injection molding, and its operation is as follows.

Close the mold: Make sure that there are no foreign matters, and close the fixed mold 21 and the movable mold 22 which are dies at low pressure. Mold clamping: The fixed mold 21 and the movable mold 22 are clamped at high pressure so as not to be opened by injection pressure. Injection: Injection cylinder 23 with screw 19 inside
The pellets 24 of the liquid crystal polymer put into the inside through the hopper 25 are melted by the heater 26, and the melt is injected into the cavity 18 through the screw 19. Holding pressure: The pressure in the injection cylinder 23 is maintained at a high pressure. Cooling and curing (plasticization): The pressure in the injection cylinder 23 is reduced, and the liquid crystal polymer in the movable mold 22 is plasticized by heating. Mold opening: Opening the fixed mold 21 and the movable mold 22 Release and molding.

Although the liquid crystal polymer is not particularly limited, for example, a liquid crystal polyester is preferable. This liquid crystal polyester can be selected from various known ones, and is a copolymer of two or more monomers, and almost all of them are

Embedded image (Hereinafter abbreviated as OBA component), which accounts for 50 mol% or more of the whole (except for this OBA component).
Some do not contain a BA component).

As described above, the fact that the copolymer is the above-mentioned OBA component in an amount of 50 mol% or more exhibits advantageous properties useful for the present invention.

The bonding mode of the liquid crystal polyester is generally only an ester bond (polyester). However, an amide bond, an imide bond, a carbonate bond, a urethane bond, or the like may be introduced.

Since the liquid crystal polymer does not use environmentally harmful substances such as halogens as compared with the epoxy resin, the environment is not impaired and there is no problem in use.

Further, in the liquid crystal polymer, the molecular chains are oriented in the flow direction at the time of molding, and a reinforcing effect is produced, and high strength and elastic modulus can be obtained. And despite the high modulus,
It shows excellent vibration absorption characteristics, especially the coefficient of linear expansion in the flow direction is much smaller than that of ordinary plastic, comparable to metal, and the thinner the molded product, the larger the proportion of the surface orientation layer, High strength and elastic modulus can be obtained. In addition, since it has a dense crystal structure, it exhibits a high deflection temperature under load, a continuous use temperature, heat resistance, and a low water absorption despite its relatively low melting point (FIG. 4).
reference).

Step (B): This is a chemical alkali etching step, which aims to moderately roughen the surface of the liquid crystal polymer housing and enhance the adhesion of a metal plating film described later by an anchoring effect. As the alkali used for this treatment, for example, potassium hydroxide is preferable. This etching process is performed on the inner and outer surfaces 1a and 1b of the housing 1.
This etching is not always necessary in the present invention.

Step (C): This is a secondary molding step in which, for example, polyvinyl alcohol 2 is adhered to a desired portion on the inner surface 1a of the housing 1 using a predetermined mask. This material is a material that is easily soluble in water or hot water, and the portion covered with the material is a portion that is not coated with a catalyst as described later, and thus is not coated with metal plating.

Step (D): a step of performing a catalyst treatment using a pattern. For this purpose, for example, palladium chloride is used as a catalyst, and this catalyst is not covered with the polyvinyl alcohol (exposed portion of the primary material) 1b,
1c.

Step (E) (see FIG. 2): This is a step of secondary side dissolution. As described above, the polyvinyl alcohol 2 is dissolved using water or hot water.

Step (F): a step of performing metal plating. The method is not particularly limited, but in practice, electroless plating is preferred. The configuration of the plating layer may be a single layer or a plurality of layers. Also, the metal to be plated may be a metal known in the art. For example, Au / Ni / Cu as a three-layer structure
/ It is better to use the base metal surface.

By applying this metal plating, the circuit pattern 3 is formed on the pattern of the catalyst layer 1 c on the inner surface 1 a of the housing 1, and the outer surface 1 b, the so-called appearance surface, is covered with the metal plating film 4. become. The formation of the circuit pattern 3 and the step of forming the plating film on the outer surface 1b can be performed individually, but are preferably performed simultaneously from the viewpoint of efficiency.

Step (G): A resist process and a solder process are performed on the inner surface 1a of the housing, and a solder 5 is formed on the circuit pattern 3 and a resist 6 is formed on a portion where the plating film is not covered.

Step (H): Here, on the outer surface 1b side,
The coating film 7 is formed on the metal plating film 4 by, for example, spray coating or roller coating. The plating film 4 has already been formed on the outer surface 1b in the step (F), and the coating film 7 is strongly adhered to this.

Step (I): An electronic component, for example, a resistor chip 8 is fixed to the solder 5. At this time, it is necessary to reflow the solder 5 by applying heat.

Step (J): Lower case 9 thus manufactured
And the upper case 10 in which the metal plating and painting are applied to the appearance surface in another process similar to the above. For this joining, for example, an ultrasonic vibration horn (vibrating part) 11 is preferably applied, and an ultrasonic welding method is performed.

The above is only a preferred embodiment of the present invention, and the present invention can take various embodiments without departing from the gist of the present invention.

[0037]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is limited thereto.

Example 1 (1) Production of Resin Molded Product Powdery liquid crystalline polyester (manufactured by Polyplastics Co., Ltd.)
Vectra) was melt-kneaded at a temperature of 300 to 360 ° C. using an extruder to obtain 6 mmφ pellets. At this time, the screw rotation speed of the extruder is set at 50 to prevent heat generation and decomposition of the resin.
0 rpm or less.

Next, using an injection molding machine (1S75E, manufactured by Toshiba Corporation) as shown in FIG. 5, the pellets were put into the hopper, and the temperature of the injection cylinder was adjusted to 250 to 33.
0 ° C. (the temperature was increased stepwise from the hopper side to the mold side), the mold temperature was 150 ° C., and the injection pressure was 140 kg / cm.
^2, and a casing as shown in FIG. 6 was formed. Then, the following seven kinds of casing samples were prepared by changing the type of the liquid crystal polyester, adding an additive, and further subjecting the molded article to surface treatment (alkali etching, plating treatment based on the present invention, and the like). .

(1) C820 (Plating grade with improved surface properties) (2) A410 (Low anisotropy grade) (3) A950 (Unfilled grade) (4) B130 (Glass fiber reinforced ultra-high rigidity grade) (5) LCX364 (fluidity improving grade) (6) C810 (standard plating (Cu / Ni / Au) grade): equivalent to the present invention (7) C810 (surface alkali etching + plating treated article): equivalent to the present invention

Coating conditions: The sample was coated using the following two types of coatings separately. Prior to this painting,
The surface was carefully wiped with isopropyl alcohol (IPA). (A) Acrylic / silicone paint (Altipa World, manufactured by Musashi Paint Co., Ltd.) Compounding ratio: Main agent (antipa world black 787):
Curing agent (787-10B): thinner (anti-pa world thinner 27885) = 10: 1: 8 (weight ratio) (b) Primer for electroless plating (MPC super primer) Compounding ratio: main agent (super primer clear): Curing agent (8954NY): Thinner (Super Primer Thinner 2868) = 10: 1: 4 (weight ratio) Note) Numerical values in parentheses indicate part numbers.

(3) Test items and conditions: The peeling and adhesion tests of the coating film were performed under the conditions shown in the following table.

[Table 1]

(4) Test Results The results of the above tests are shown in the table below when acrylic / silicone paint is used as the paint.

[Table 2] ○… Pass ×× Peeling Note) When all of the three samples are non-defective, "○", 1
If the test was not successful, it was rated "x".

As apparent from the above, the coating film was uniformly peeled off on the non-plated surface of the housing, but the coating film had a strong adhesive force on the plated surface, and showed good results as an exterior product. In addition, when the primer for electroless plating was used as the paint, the same result as described above was obtained.

[0045]

As described above, according to the present invention, a metal film is formed on a molded body made of a liquid crystal polymer, and the surface of the metal film is coated. A coating film that is difficult to perform can be obtained with a reduced number of steps.

In particular, for electronic and electric products, by leaving a non-painted portion for a wiring circuit when coating a resin molded body such as a housing, the painted portion is used for improving the appearance, and the unpainted portion is used for improving the appearance. It is possible to provide a highly productive resin molded product having a function for an electronic circuit or the like and an exterior and a function integrated with high efficiency.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view sequentially showing a housing manufacturing process based on the present invention.

FIG. 2 is a longitudinal sectional view showing a continuation of the process.

FIG. 3 is a longitudinal sectional view showing a further continuation of the process.

FIG. 4 is a table showing physical properties of a liquid crystal polymer in comparison with other polymer compounds.

FIG. 5 is a schematic sectional view showing an injection molding machine for molding a housing based on the present invention and its operation.

FIG. 6 is a perspective view of the molded housing.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing, 1a ... Inner surface, 1b ... Outer surface, 1c ... Catalyst penetration part, 2 ... Polyvinyl alcohol, 3 ... Circuit pattern, 4
... metal plating film, 5 ... solder, 6 ... resist, 7 ... coating film, 8 ... chip, 9 ... lower case, 10 ... upper case, 11
... horn, 18 ... cavity, 19 ... screw, 20
... Injection molding machine, 21 ... Fixed mold, 22 ... Movable mold, 23 ... Injection cylinder, 24 ... Pellet, 25 ... Hopper, 26
…heater

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/02 H05K 1/02 A 5E343 3/18 3/18 E 3/34 507 3/34 507C 5 / 02 5/02 J (72) Inventor Hirokazu Nakayoshi 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 4D075 AA01 BB87X CA04 CA18 CA21 DA23 DB48 DC19 DC22 EA05 4E360 AA02 AB02 AB42 EE02 EE12 EE13 GA06 GA51 GB26 GB97 GC08 4F100 AB00B AK25 AK41A AK52 AL05 AS00A AT00A BA03 BA07 BA10C CA02 CC00C EH36 EH71B GB41 JK06 JL11 5E319 AA03 AC02 BB05 CC33 5E338 AA05 AA16 BB05 BB17 BB17 BB17 BB17 BB17 BB17 BB17 BB75 FF01 FF16 FF27

Claims (13)

[Claims] 1. A method for coating a resin molded article, comprising forming a metal film on a molded article made of a liquid crystal polymer, and applying a coating on the surface of the metal film. 2. The method according to claim 1, wherein the metal film is a metal plating film, and the liquid crystal polymer is a liquid crystal polyester. 3. The method for coating a resin molded article according to claim 1, wherein the molded article is a housing of an electronic device, and the coating is applied to a appearance surface of the housing. 4. The method according to claim 3, wherein the housing is a memory stick housing or a mobile phone housing. 5. A metal film is formed on each of an inner surface and an outer surface of the casing made of the liquid crystal polymer, and among these, the inner metal film is used for a wiring circuit, and the coating is applied to the outer metal film. A method for coating a resin molded article according to claim 1. 6. The step of forming the wiring circuit made of a metal plating film on the inner surface of the housing and the step of forming a metal plating film on the outer surface of the housing are performed simultaneously.
The method for coating a resin molded article according to the above. 7. The method according to claim 5, wherein an electronic component is mounted on the wiring circuit on the inner surface of the housing. 8. A coated article in which a metal film is formed on a surface of a molded body made of a liquid crystal polymer, and a coating is applied on the metal film. 9. The coated article according to claim 8, wherein the metal film is a metal plating film, and the liquid crystal polymer is a liquid crystal polyester. 10. The electronic device according to claim 10, wherein the molded body is a housing of an electronic device.
The said coating is given to the appearance surface of this housing | casing.
Painted products described in. 11. The coated article according to claim 10, wherein the housing is a memory stick housing or a mobile phone housing. 12. A wiring circuit made of a metal plating film is formed on the inner surface of the casing made of the liquid crystal polymer, and a metal plating film is formed on the outer surface. The coating is applied to the surface of the metal plating film. The coated article according to claim 8, wherein 13. The painted product according to claim 12, wherein an electronic component is mounted on the wiring circuit on the inner surface of the housing.