JP2013227617A - Method for manufacturing formed body having plating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a formed body having a plating film which has high adhesive strength as initial characteristics, durability and reliability over a long period of time, and excellent appearance characteristics.SOLUTION: A method for manufacturing a formed body having a plating film includes a step of preparing the formed body consisting of a polyamide resin containing metal particles, a step of bringing weak acid into contact with the formed body, and a step of forming the plating film by bringing electroless plating liquid into contact with the formed body with which the weak acid is brought into contact.

Description

  The present invention relates to a method for producing a molded body having a plating film.

  An electroless plating method is known as a method for forming a metal film on a molded body at low cost. In the electroless plating method, a pretreatment for roughening the surface of the molded body is performed using an etching solution containing an oxidizing agent such as hexavalent chromic acid or permanganic acid in order to ensure adhesion of the metal film to the molded body. Therefore, an ABS resin (acrylonitrile / butadiene / styrene copolymer synthetic resin) that is eroded by an etching solution has been mainly used in the electroless plating method. In the ABS resin, the butadiene rubber component is selectively eroded by the etching solution, and irregularities are formed on the surface. On the other hand, for a resin other than the ABS resin, for example, polycarbonate, a plating grade in which a component that is selectively oxidized to an etching solution such as an ABS resin or an elastomer is mixed in order to enable electroless plating. However, the pretreatment of such an electroless plating method has a problem of high environmental load because hexavalent chromic acid, permanganic acid or the like is used.

  On the other hand, as a method for forming a metal film on a molded body without passing through the pretreatment etching step, use of a surface modification method of the molded body using pressurized carbon dioxide such as supercritical carbon dioxide has been proposed. Yes. The present inventors have proposed a method of performing surface modification treatment using pressurized carbon dioxide at the same time as injection molding, and dispersing palladium serving as a catalyst core for electroless plating near the surface of the molded body (patent) Literatures 1-3). In this method, a plating film can be formed on the surface of the molded body without performing an etching step by performing electroless plating on the molded body having palladium unevenly distributed on the surface.

Japanese Patent No. 4160623 Japanese Patent No. 3696878 JP 2010-30106 A

  When the electroless plating solution is brought into contact with the molded body containing the catalyst described in Patent Documents 1 to 3, the plating solution penetrates from the surface of the molded body into contact with the metal fine particles, and the inside of the molded body. The plating film grows while spreading the molded body. For this reason, the plating film has high adhesion strength.

  On the other hand, there are various uses of the molded body having a plated film. For example, in decorative applications, not only the adhesion strength of the plated film but also a high quality appearance is required. In addition, a molded body having a plated film often requires not only initial characteristics but also durability and reliability over a long period of time.

  The present invention solves these problems, and has a high adhesion strength as an initial characteristic, a durability and reliability over a long period of time, and a molded article having an excellent appearance characteristic. A manufacturing method is provided.

  According to an aspect of the present invention, there is provided a method for producing a molded body having a plating film, comprising preparing a molded body made of a polyamide resin containing metal fine particles, bringing a weak acid into contact with the molded body, and the weak acid. There is provided a method for producing a molded body having a plated film, which comprises contacting the molded body in contact with an electroless plating solution to form a plated film.

  The present invention can produce a molded article having a plating film having high adhesion strength as an initial characteristic, durability and reliability over a long period of time, and excellent appearance characteristics.

It is a flowchart which shows the manufacturing method of the molded object which has a plating film manufactured in embodiment. 1 is a schematic view of a molding machine used in Example 1. FIG. It is a schematic sectional drawing of the plasticization cylinder of the molding machine used in Example 1, and is a figure which shows the state which the plasticization zone, the high pressure kneading zone, and the pressure reduction zone connected. It is a schematic sectional drawing of the plasticization cylinder of the molding machine used in Example 1, and is a figure which shows the state by which the communication of the plasticization zone, the high pressure kneading zone, and the pressure reduction zone was interrupted | blocked. In Example 1, 2, and Comparative example 1 and 2, it is a figure which shows the relationship between the leaving time when each produced sample is left to stand in a high-temperature, high-humidity environment, and the adhesion strength of the plating film of a sample. (A) is a laser micrograph of the surface of the sample produced in Example 3, and (b) is a laser micrograph of the surface of the sample produced in Comparative Example 3. 6 is a SEM photograph of a cross section of a sample manufactured in Comparative Example 3.

  A method for producing a molded body having a plated film according to an embodiment of the present invention will be described with reference to FIG. First, a molded body made of a polyamide resin containing metal fine particles is prepared (step S1).

  The metal fine particles function as a plating catalyst, and metal fine particles such as Pd, Ni, Pt, and Cu, metal oxides, and metal oxide precursors such as metal alkoxides can be used. The type of metal complex is arbitrary, but more specifically, hexafluoroacetylacetonato palladium (II), platinum dimethyl (cyclooctadiene), bis (cyclopentadienyl) nickel, bis (acetylacetonate) palladium. Etc. are desirable.

  As the polyamide resin, nylon having high water absorption and plating reactivity is preferable, and 6 nylon and 6,6 nylon are particularly preferable. The molded body produced in the present embodiment may contain a thermoplastic resin other than the polyamide resin, but the polyamide resin is preferably the main component. Examples of the thermoplastic resin other than the polyamide resin include polypropylene, polymethyl methacrylate, polycarbonate, amorphous polyolefin, polyether imide, polyethylene terephthalate, polyethylene ether ketone, ABS resin, polyphenylene sulfide, polyamide imide, polylactic acid, and polycaprolactone. Etc. can be used.

  Moreover, various inorganic fillers, such as a mineral, glass fiber, a talc, a carbon fiber, can also be kneaded with a polyamide resin. By blending a mineral or the like with the polyamide resin, it is possible to suppress warping of the molded body and improve rigidity and dimensional stability.

  In the present embodiment, the metal fine particles functioning as a plating catalyst are preferably unevenly distributed near the surface of the molded body. In the present embodiment, when an electroless plating solution is brought into contact with the molded body in an electroless plating step (step S3) described later, since the plating catalyst is contained inside the molded body, the plating solution penetrates from the surface of the molded body. Thus, the plating film grows from the inside of the molded body in contact with the metal fine particles. Therefore, when the concentration of the metal fine particles near the surface of the molded body is increased, the plating reaction proceeds efficiently. Further, by reducing the concentration of the metal fine particles present in the central portion of the molded body that does not contribute to the plating reaction, waste of material can be eliminated and material cost can be reduced.

  In the present specification, the “near the surface of the molded body” means an area inside the molded body and close to the surface. When the molded body is brought into contact with the plating solution, the plating solution is exposed from the surface. It means the area where plating penetrates and plating reaction occurs. The extent to which “near the surface of the molded body” means the region from the surface of the molded body varies depending on the type of resin used in the molded body. A region having a depth of 1 to 10 μm.

  The molded body used in the present embodiment may be manufactured through a process in which metal fine particles are dissolved or dispersed in pressurized carbon dioxide, and the pressurized carbon dioxide in which the metal fine particles are dissolved or dispersed is brought into contact with the polyamide resin. When metal fine particles are contained in the polyamide resin using pressurized carbon dioxide, the metal fine particles can be unevenly distributed at a depth of about 1 to 5 μm from the outermost surface of the molded body made of the polyamide resin. Moreover, the particle diameter of the metal fine particles serving as catalyst nuclei can be remarkably reduced, and a molded article having high plating reactivity can be manufactured. Examples of the method for producing a molded article containing metal fine particles using pressurized carbon dioxide include the methods disclosed in the above-mentioned Patent Documents 1 to 3.

  For example, in a molded body, a polyamide resin is plasticized and melted in a plasticizing cylinder of an injection molding machine or an extrusion molding machine, and pressurized carbon dioxide in which metal fine particles are dissolved is introduced into the plasticizing cylinder. The polyamide resin and the pressurized carbon dioxide may be mixed and then molded. As another method, pressurized carbon dioxide in which metal fine particles are dissolved or dispersed in advance is introduced into a mold of an injection molding machine, and a polyamide resin that has been plasticized and melted is injected and filled therein. The resin may be produced by bringing pressurized carbon dioxide into contact with the resin and containing fine metal particles in the molded body. Further, the contact between the pressurized carbon dioxide and the polyamide resin is not necessarily performed during the molding process of the polyamide resin. For example, a polyamide resin is first molded to obtain a molded body, and then the molded body is placed in a high-pressure container, and in the high-pressure container, pressurized carbon dioxide in which metal fine particles are dissolved or dispersed is brought into contact. The metal fine particles may be infiltrated in the vicinity of the surface of the molded body.

  Thus, when manufacturing a molded object through the process of melt | dissolving a metal microparticle in pressurized carbon dioxide, a metal microparticle is hexafluoroacetylacetonato palladium (II), bis (cyclopentadienyl) nickel, Bis (acetylacetonato) palladium (II), dimethyl (cyclooctadienyl) platinum (II), hexafluoroacetylacetonatohydrate copper (II), hexafluoroacetylacetonatoplatinum (II), hexafluoroacetylacetonato ( Trimethylphosphine) silver (I), dimethyl (heptafluorooctaneoneate) silver (AgFOD), or the like can be used. In particular, a metal complex having a ligand containing fluorine is preferable because it is easily compatible with pressurized carbon dioxide. In addition, the metal complex dissolved in pressurized carbon dioxide is reduced by removing the ligand in the manufacturing process of the molded body, and in the molded body, not as a metal complex, but as reduced metal fine particles It often exists.

  Next, a weak acid is brought into contact with the molded body containing the metal fine particles prepared as described above (step S2). In the present embodiment, the step of bringing a weak acid into contact with the molded product corresponds to a pretreatment for plating for forming a plating film on the molded product. Although some of the metal fine particles are considered to be exposed on the surface of the molded body, more metal fine particles can be exposed on the surface of the molded body by etching the surface of the molded body made of polyamide resin with a weak acid. it can. By exposing more metal fine particles to the surface of the molded body, it becomes easier to form a plating film on the surface of the molded body, and the time for forming the plating film can be shortened. By shortening the plating film formation time, defects in the plating film such as pinholes are less likely to occur.

  However, the pretreatment for plating with a weak acid in the present embodiment is different from the conventional plating pretreatment for roughening the surface of the molded body. As a conventional pretreatment for plating, there is known a method in which ABS resin, elastomer, mineral or the like is contained in the resin and these are removed from the surface of the molded body with an etching solution having high environmental load such as hexavalent chromic acid or permanganic acid. ing. Therefore, in the conventional plating pretreatment, irregularities are formed on the surface of the molded body. On the other hand, the pretreatment of the plating with the weak acid slightly dissolves the surface of the molded body and exposes the metal fine particles to the surface of the molded body, and does not roughen the surface of the molded body.

  The weak acid used in the present embodiment is an acid that dissolves the polyamide resin. For example, acetic acid, formic acid, butyric acid, lauric acid, lactic acid, malic acid, citric acid, oleic acid, linoleic acid, benzoic acid, oxalic acid, It is a kind selected from the group consisting of carboxylic acids such as succinic acid, malonic acid, maleic acid, tartaric acid and amino acids, and phosphoric acid, boric acid, hypochlorous acid, hydrogen fluoride and hydrogen sulfide. The weak acid used in the present embodiment is preferably acetic acid or phosphoric acid from the viewpoints of dissolving the polyamide resin but not eroding so much as to destroy the resin, and environmental and ease of handling by the operator.

  The weak acid used in the present embodiment is an acid that dissolves the polyamide resin, but does not include strong acids such as hydrochloric acid, sulfuric acid, and nitric acid. Although it is possible to etch the surface of the molded body using a strong acid, the strong acid remains on the surface of the molded body and in the vicinity of the surface, corrodes both the molded body and the plated film, and decreases the durability of the molded body. Further, when the pH is lowered by diluting strong acids such as hydrochloric acid, sulfuric acid and nitric acid in order to solve the corrosion problem, these strong acids lose the ability to etch the molded body. On the other hand, the weak acid used in the present embodiment has an ability to etch a molded body made of a polyamide resin, and does not cause a corrosion problem for both the molded body and the plated film. Therefore, when the pre-plating treatment of the molded body containing metal fine particles is performed with a weak acid, the formation of a plating film can be promoted by exposing many metal fine particles to the surface of the molded body by etching, and the durability of the molded body is also improved. In addition, the weak acid used in the present embodiment has a lower environmental load than a strong acid and is easy to handle, so that the operator's risk is reduced and workability is improved.

  Furthermore, performing the plating pretreatment of the molded body containing the metal fine particles with a weak acid has the following effects. In the case where a mineral is contained in a polyamide resin for the purpose of suppressing warpage of the molded body and improving rigidity and dimensional stability, the present inventors perform a plating pretreatment using a strong acid to form a plating film on the surface of the molded body. It was discovered that a large number of unplated portions that were not formed occurred. And it discovered that generation | occurrence | production of this unplated part can be suppressed by using a weak acid for the plating pretreatment of a molded object. The reason for this is not clear, but is presumed as follows. When a strong acid is used for the plating pretreatment, a strong acid and a mineral contained in the molded body react, and for example, a phenomenon that adversely affects a plating reaction occurs, for example, the mineral dissolves to generate gas. On the other hand, since the weak acid used in this embodiment does not react with minerals in this manner, it is considered that a plating non-deposited portion does not occur and a plating film having excellent appearance characteristics can be formed.

  Examples of minerals added to the polyamide resin include silicates such as calcium silicate, aluminum silicate, magnesium silicate, and silicon dioxide, silicic acid, calcium oxide, calcium carbonate, magnesium oxide, magnesium hydroxide, and barium sulfate. And at least one selected from the group consisting of compounds (minerals) containing the same. In particular, silicates such as calcium silicate and magnesium hydroxide are preferable from the viewpoints of surface properties (appearance), mechanical strength, dimensional stability, and cost. Similarly, calcium oxide and silicon dioxide are also preferable as minerals used in this embodiment. Examples of commercially available polyamide resins containing such minerals include Toyobo, Mineral Reinforced Resin T777-02, Ube Industries, Mineral Reinforced Resins 1013R, 1013R1, and the like. It is preferable to add the mineral to the polyamide resin so that the content in the molded article to be molded is 10 to 50 vol%. The manufacturing method of the molded body of this embodiment is suitable as a manufacturing method of the molded body which consists of a polyamide resin containing such a mineral.

  Next, an electroless plating solution is brought into contact with the molded body that has been subjected to pre-plating treatment with a weak acid to form a plating film (step S3 in FIG. 1). As the electroless plating solution, a known one can be used, but an electroless nickel phosphorous plating solution is preferable from the viewpoint that the catalyst activity is high and the solution is stable. Since the molded body manufactured in the present embodiment includes metal fine particles that function as a plating catalyst, it is not necessary to perform a plating catalyst application treatment. In addition, as described above, since the molded body manufactured in this embodiment is pre-plated using weak acid, many metal fine particles are exposed on the surface of the molded body, and a plating film is formed on the surface of the molded body. Easy to do.

  In the present embodiment, the electroless plating solution penetrates from the surface of the molded body and comes into contact with the metal fine particles contained in the molded body, and the plating film grows using the metal fine particles as a catalyst. Therefore, the plating film is formed on the molded body in a state where it has penetrated into the molded body (a part of the plating film has penetrated into the molded body), and is made of the same metal as the polyamide resin and the plating film in the vicinity of the surface of the molded body. A mixed layer with the metal region is formed. Therefore, it is not necessary to roughen the surface of the molded body unlike the conventional electroless plating method, and a plating film having excellent adhesion can be easily formed. In the present embodiment, since the surface of the molded body is not roughened as in the conventional electroless plating method, a plating film having a very small surface roughness (nano order) can be formed.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not restrict | limited by the following Example.

[Example 1]
In this example, a molding body made of polyamide resin containing metal fine particles was manufactured by injection molding using a molding machine 1000 shown in FIG. 2, and a plating film was formed on the manufactured molding body.

  Nylon 6 (manufactured by Toray Industries, Inc., CM1001G-30) mixed with 30 vol% of glass filler was used as the polyamide resin, and hexafluoroacetylacetonato palladium (II) metal complex, which is an organometallic complex, was used as the metal fine particles. .

<Molding machine>
First, a molding machine used for molding a molded body in this example will be described. As shown in FIG. 2, the molding machine 1000 includes a kneading device 200 and a pressurized carbon dioxide containing metal fine particles (hereinafter referred to as “mixed pressurized fluid” as necessary). The pressurized fluid supply device 100, a mold clamping unit 250 provided with a mold, and a control device (not shown) are provided. The control device controls operations of the pressurized fluid supply device 100, the kneading device 200, and the mold clamping unit 250.

  As the pressurized fluid supply apparatus 100, any apparatus can be used as long as the metal fine particles can be dissolved or dispersed in pressurized carbon dioxide and introduced into the kneading apparatus 200. In this embodiment, however, the pressurized fluid supply apparatus 100 is added like a syringe. A supply device equipped with a syringe pump for sucking and feeding pressurized carbon dioxide and the like was used. That is, the pressurized fluid supply device 100 is a device that supplies a mixture of pressurized carbon dioxide and metal fine particles. The pressurized carbon dioxide cylinder 101 and liquid carbon dioxide are sucked from the carbon dioxide cylinder 101 and then added. It comprises a carbon dioxide syringe pump 102 that supplies liquid carbon dioxide under pressure, a solution tank 111 that contains the metal fine particle-containing liquid C, and a solution syringe pump 112 that pressurizes and supplies the metal fine particle-containing liquid C. Each syringe pump 102, 112 is capable of pressure control and flow rate control. The piping connecting the liquid carbon dioxide cylinder 101 and the carbon dioxide syringe pump 102 and the piping connecting the carbon dioxide syringe pump 102 and the kneading device 200 are respectively the suction air operated valve 104 and the supply air operated valve 105. Is arranged. In addition, a suction air operated valve 114 and a supply air operated valve 115 are arranged on a pipe connecting the solution tank 111 and the solution syringe pump 112 and a pipe connecting the solution syringe pump 112 and the kneading apparatus 200, respectively. It is installed.

  The kneading apparatus 200 includes a plasticizing cylinder 210, a screw 20 disposed in the plasticizing cylinder 210 so as to be able to rotate and advance, and an upstream sealing mechanism S1 and a downstream sealing mechanism S2 disposed in the plasticizing cylinder 210. And a pressure-reducing zone pressure adjusting mechanism 1 connected to the plasticizing cylinder 210. Further, a shut-off valve 36 that opens and closes by driving the air cylinder 12 is provided at the nozzle tip 29 of the plasticizing cylinder 210 so that the inside of the plasticizing cylinder 210 can be held at a high pressure. A mold is brought into close contact with the nozzle tip 29, and molten resin is injected and filled from the nozzle tip 29 into a cavity 253 formed by the mold. In the present embodiment, in the plasticizing cylinder 210, the plasticized and melted molten resin flows from the right hand to the left hand in FIGS. Therefore, in the plasticizing cylinder 210, the right hand in FIGS. 2 to 4 is defined as “upstream” or “rear”, and the left hand is defined as “downstream” or “front”.

  Further, although not shown, at the rear end portion on the upstream side of the plasticizing cylinder 210, a rotation driving means such as a rotary motor for rotating the screw 20, a ball screw for moving the screw 20 forward and backward, a motor for driving the same, and the like Is connected to the moving means. As shown in FIGS. 3 and 4, when the kneading apparatus 200 is viewed from the rear side of the plasticizing cylinder 210, when the screw 20 is rotated counterclockwise, the molten resin is moved forward (nozzle part side). It is configured to perform forward rotation to be sent and to reverse rotation when rotated clockwise.

  On the upper side surface of the plasticizing cylinder 210, a resin supply port 201 for supplying polyamide resin to the plasticizing cylinder 210 in order from the upstream side, and an introduction port 202 for introducing mixed pressurized fluid into the plasticizing cylinder 210. , And a vent 203 for discharging the gasified carbon dioxide from the plasticizing cylinder 210 is formed. The resin supply port 201 and the introduction port 202 are provided with a resin supply hopper 211 and an introduction valve 212, respectively, and the vent 203 is connected to the decompression zone pressure adjusting mechanism 1. The introduction valve 212 is connected to the pressurized fluid supply apparatus 100 described above.

  In the kneading apparatus 200, polyamide resin is supplied from the resin supply port 201 into the plasticizing cylinder 210, and the polyamide resin is plasticized and melted by a band heater (not shown) disposed on the outer wall surface of the plasticizing cylinder 210. It becomes resin and is sent downstream by the screw 20 rotating forward. The molten resin sent to the vicinity of the inlet 202 is contact-kneaded with pressurized carbon dioxide (mixed pressurized fluid) containing the introduced metal fine particles under high pressure. Next, by reducing the internal pressure of the molten resin that has been kneaded in contact with the mixed pressurized fluid, the gasified carbon dioxide is separated from the molten resin, and the gasified carbon dioxide is discharged from the vent 203. Then, the molten resin sent further forward is pushed out to the tip of the screw 20, and the pressure of the molten resin becomes a reaction force against the screw 20, and the screw 20 moves backward by the reaction force so that the molten resin is measured. As a result, in the plasticizing cylinder 210, in order from the upstream side, the plasticizing zone 21 that plasticizes the polyamide resin to form a molten resin, the molten resin and the mixed pressurized fluid introduced from the inlet 202 are brought into contact under high pressure. A high pressure kneading zone 22 for kneading and a pressure reducing zone 23 for discharging carbon dioxide separated from the molten resin from the vent 203 are formed by lowering the internal pressure of the molten resin kneaded in contact with the mixed pressurized fluid. Further, a repressurization zone 24 is provided downstream of the decompression zone 23. In the re-pressurization zone 24, the molten resin is sent to the front of the screw and is measured.

  As shown in FIGS. 2 to 4, the upstream side that temporarily cuts off the communication state of the zones 21, 22, and 23, respectively, between the plasticizing zone 21, the high-pressure kneading zone 22, and the decompression zone 23. A seal mechanism S1 and a downstream seal mechanism S2 are provided. Thereby, for example, when the mixed pressurized fluid is introduced into the high-pressure kneading zone 22, the upstream side and the downstream side of the high-pressure kneading zone 22 are mechanically sealed to ensure that the zones 21 and 23 adjacent to the high-pressure kneading zone 22 are surely. Can be shut off. As a result, the pressure in the high-pressure kneading zone 22 is maintained at a high pressure, so that the metal fine particles can effectively penetrate into the molten resin. Various upstream sealing mechanisms S1 and downstream sealing mechanisms S2 can be used as long as they block communication between the zones 21, 22, and 23. In this embodiment, the screw 20 is rotated as described later. Accordingly, the one that cut off the communication between these zones was used.

  The decompression zone pressure adjustment mechanism 1 always maintains the pressure in the decompression zone at a substantially constant pressure. The depressurization zone pressure adjusting mechanism 1 includes a buffer container 5 and an exhaust mechanism that is connected from the connection port 5 a of the buffer container 5 to the exhaust port 11 via the pressure gauge 4 and the back pressure valve 3. The depressurization zone pressure adjusting mechanism 1 controls the pressure inside the depressurization zone 23 by setting the back pressure valve 3 of the exhaust mechanism to a predetermined value and limiting the exhaust amount of carbon dioxide gas. Thus, the decompression zone pressure adjustment mechanism 1 controls the gas pressure in the decompression zone 23. By maintaining the pressure in the decompression zone constant by the decompression zone pressure adjusting mechanism 1, the amount of pressurized carbon dioxide introduced into the plasticizing cylinder 210 can be stably controlled every shot.

  Next, the upstream side seal mechanism S1 and the downstream side seal mechanism S2 will be described. As shown in FIGS. 3 and 4, the plasticizing screw 20 has a reduced diameter portion 50 that is reduced in diameter in the boundary region between the high-pressure kneading zone 22 and the decompression zone 23 as compared with a region adjacent to the boundary region. doing. A downstream seal ring 60 is externally fitted to the reduced diameter portion 50 in a loosely fitted state so as to be movable in the axial direction (front-rear direction) within the range of the reduced diameter portion 50. The reduced diameter portion 50 and the downstream seal ring 60 constitute a downstream seal mechanism S2. Similarly, in the boundary region between the plasticizing zone 21 and the high-pressure kneading zone 22, the reduced diameter portion 30 and the upstream seal ring 40 constitute an upstream seal mechanism S1. In the present embodiment, the upstream side seal mechanism S1 and the downstream side seal mechanism S2 have basically the same configuration. A metal outer seal member 70 is fitted on the outer peripheral surface of the downstream seal ring 60 so as to protrude from the outer peripheral surface of the downstream seal ring 60. Thereby, the sealing performance between the downstream seal ring 60 and the plasticizing cylinder 210 is ensured. Similarly, an outer seal member 80 is fitted on the outer peripheral surface of the upstream seal ring 40.

  The reduced diameter portion 50 of the plasticizing screw 20 includes a truncated cone portion (seal portion) 51 having a tapered surface inclined toward the front (downstream), and a horizontal plane that is connected to the truncated cone portion 51 and extends horizontally in the axial direction. And a cylindrical portion 52 having the same. Similarly, the reduced diameter portion 30 also includes a truncated cone portion (seal portion) 31 and a cylindrical portion 32.

  As shown in FIG. 3, when the screw 20 is rotated forward (counterclockwise), the upstream side and downstream side seal rings 40 and 60 move to the downstream side in the range of the reduced diameter portions 30 and 50, respectively. When the downstream seal ring 60 moves downstream with respect to the screw 20, the seal portion 51 of the reduced diameter portion 50 and the downstream seal ring 60 are separated from each other, and a gap serving as a runway for the molten resin and pressurized carbon dioxide G is formed, whereby the high-pressure kneading zone 22 and the decompression zone 23 communicate with each other. Similarly, when the screw 20 is rotated forward (counterclockwise), a gap G is formed in the upstream side seal mechanism S1, and the plasticizing zone 21 and the high-pressure kneading zone 22 communicate with each other.

  On the other hand, as shown in FIG. 4, when the screw 20 is rotated backward (clockwise) at a predetermined rotational speed or more, the downstream seal ring 60 moves upstream with respect to the screw 20. When the downstream seal ring 60 moves upstream with respect to the screw 20, the seal portion 51 of the reduced diameter portion 50 and the downstream seal ring 60 come into contact with each other, and the gap G disappears. Thereby, the communication between the high-pressure kneading zone 22 and the decompression zone 23 is blocked. Similarly, when the screw 20 is rotated in the reverse direction (clockwise), the gap G of the upstream side seal mechanism S1 disappears and the communication between the plasticizing zone 21 and the high-pressure kneading zone 22 is blocked.

<Molding method of molded body>
Using the molding machine 1000 shown in FIG. 2 described above, a molded body was molded by the method described below. First, the suction air operated valve 104 is opened, and liquid carbon dioxide is sucked from the liquid carbon dioxide cylinder 101. Next, liquid carbon dioxide is pressurized to a predetermined pressure by pressure control of the carbon dioxide syringe pump 102. In this example, the head of the carbon dioxide syringe pump 102 and the intermediate path were cooled to 10 ° C. to prepare pressurized carbon dioxide having a pressure of 10 MPa and a temperature of 10 ° C.

  Further, the suction air operated valve 114 on the solution syringe pump 112 side is opened, and the solution C in which metal fine particles are dissolved in the solvent is sucked from the solution tank 111 at room temperature, and the pressure is controlled by the solution syringe pump 112. Pressurize solution C to pressure. In this example, perfluorotripentylamine (manufactured by Sincrest Laboratories, Inc., molecular formula: C15F33N, molecular weight: 821.1, boiling point: 220 ° C.) was used as the solvent of the solution C, and the solution C was pressurized to 10 MPa.

  Next, after the supply air operated valves 105 and 115 are opened, the carbon dioxide syringe pump 102 and the solution syringe pump 112 are switched from pressure control to flow control, and the pressurized carbon dioxide and the pressurized solution C are predetermined. It is made to flow so that it may become the flow rate ratio. As a result, the pressurized carbon dioxide and the solution C are mixed in the pipe, and the system up to the introduction valve 212 for introducing the high-pressure fluid into the plasticizing cylinder 210 is pressurized. In this example, the concentration of the metal fine particles in the mixed pressurized fluid was controlled to about 10 to 20% of the saturation solubility.

  On the other hand, in the kneading apparatus 200, the polyamide resin is supplied from the resin supply hopper 211, the plasticizing zone 21 is heated by a band heater (not shown) provided on the outer wall surface of the plasticizing zone 21, and the screw 20 is adjusted. Rotated. Thereby, the polyamide resin was heated and kneaded to obtain a molten resin. In this example, the plasticizing zone 21 of the plasticizing cylinder 210 was heated so that the temperature of the molten resin was 210 to 240 ° C.

  By rotating the screw 20 forward, the molten resin was caused to flow from the plasticizing zone 21 to the high-pressure kneading zone 22. And in order to interrupt | block the high pressure kneading | mixing zone 22, the pressure reduction zone 23, and the plasticization zone 21, rotation of the screw 20 was once stopped, Then, the screw 20 was reversely rotated. As a result, the upstream and downstream seal rings 40 and 60 are moved upstream, and the gap G between the upstream and downstream seal rings 40 and 60 and the reduced diameter portions 30 and 50 of the screw 20 is eliminated. The high-pressure kneading zone 22 was cut off from the decompression zone 23 and the plasticizing zone 21.

  After the high-pressure kneading zone 22 is sealed by the upstream and downstream sealing mechanisms S 1 and S 2, the introduction valve 212 is opened in accordance with the driving of the syringe pumps 102 and 112, and mixed and pressurized to the plasticizing cylinder 210 through the introduction port 202. Fluid was introduced. In this example, a mixed pressurized fluid having a pressure of 10 MPa and a temperature of 10 ° C. was introduced at 2.5 wt% with respect to one shot (weight 75 g) of the molded body, and the metal complex was dispersed at a set amount by 100 ppm in the molten resin.

  On the other hand, the pressure in the decompression zone 23 was controlled to a constant pressure by the decompression zone pressure adjusting mechanism 1. The set pressure of the decompression zone 23 is arbitrary, but if the metal fine particles are dissolved in the pressurized carbon dioxide, they are discharged from the vent port 203 together with the pressurized carbon dioxide. A pressure is preferred. In addition, since the molded product foams as the pressure increases, the lower the pressure, the better for the purpose of avoiding foaming. On the other hand, when the set pressure in the decompression zone 23 is too low, the pressure change when the mixed high-pressure fluid is introduced becomes large, and the variation between shots becomes large. When the metal fine particles do not change in the reduced pressure zone 23, in view of the above, the appropriate pressure of the reduced pressure sone 23 is preferably 0.5 to 6 MPa. More preferably, it is 1-4 MPa. In this example, the back pressure valve was set to 2 MPa, and the pressure in the decompression zone 23 was always controlled to 2 MPa.

  After the mixed pressurized fluid introduced into the high-pressure kneading zone 22 is dispersed in the molten resin in a high-pressure state in the high-pressure kneading zone 22, the screw 20 is rotated forward (rotation direction in which the screw is plasticized), or the screw 20 The high-pressure kneading zone 22 and the decompression zone 23 were made to communicate with each other by reducing the number of reverse rotations. In this embodiment, the number of reverse rotations of the screw 20 is reduced, and the upstream and downstream seal rings 40 and 60 are returned to their original downstream positions, and the upstream and downstream seal rings 40 and 60 and the screw are returned to the original position. The 20 diameter-reduced portions 30 and 50 were separated from each other, a gap G was formed, and the high-pressure kneading zone 22 and the decompression zone 23 were communicated. Next, the screw 20 was returned to the normal rotation, and the molten resin was flowed to the decompression zone 23.

  The molten resin and mixed pressurized fluid that flowed to the decompression zone 23 were reduced in pressure to the set pressure of the decompression zone, 2 MPa. Thus, excess pressurized carbon dioxide was gasified and separated from the molten resin, and then discharged from the exhaust port 11 of the decompression zone pressure adjusting mechanism 1 through the vent 203 of the plasticizing cylinder 210.

  Next, in the re-pressurization zone 24 set to 240 ° C., the molten resin was sent to the tip of the plasticizing cylinder 210 to complete the plasticizing measurement. Thereafter, the shut-off valve 36 was opened, molten resin was injected and filled into the cavity 253, and pressure was applied to the mold to obtain a molded body.

<Plating pretreatment>
Next, the obtained compact containing the metal fine particles was immersed in 6.0 mol / L acetic acid at 40 ° C. for 10 minutes. After being immersed in acetic acid, the molded body was washed with pure water.

<Plating treatment>
The molded body that had been subjected to the plating pretreatment was immersed in an electroless nickel phosphorus plating solution (Okuno Pharmaceutical Co., Ltd., Top Nicolon RCH-LF) at 70 to 90 ° C. for 15 minutes to form a nickel phosphorus plating film. Next, the molded body on which the nickel phosphorus plating film was formed was immersed in a substitution copper plating solution (ANC Acti, manufactured by Okuno Pharmaceutical Co., Ltd.) for 1 minute at room temperature to form a copper plating film. Thereafter, the molded body on which the copper plating film was formed was placed in an electric furnace and annealed at 80 ° C. for 12 hours.

  Next, an activator solution having a concentration of 100 g / L was prepared using an activator (Okuno Pharmaceutical Co., Ltd., Topsun). The formed article subjected to the annealing treatment was immersed in the prepared activator solution at room temperature for 5 minutes, and the metal film on the formed article was activated. By this treatment, the oxide film formed on the outermost surface of the molded body by annealing was removed.

A 20 μm copper plating film was formed by a general-purpose method on the molded body subjected to the activation treatment. As the electrolytic copper plating solution, a copper sulfate bath containing copper sulfate, sulfuric acid, hydrochloric acid and a brightener was used, the bath temperature was 30 ° C., and the current density was 3 A / dm ² . Furthermore, a 20 μm nickel plating film was formed on the electrolytic copper plating film by a general-purpose method. As the electrolytic nickel plating solution, a Watt bath containing nickel sulfate, nickel chloride, boric acid and a brightener was used, the bath temperature was 55 ° C., and the current density was 3 A / dm ² .

  The molded body on which the electrolytic plating film was formed as described above was placed in an electric furnace and annealed at 80 ° C. for 12 hours to obtain a sample of this example.

<Evaluation of sample>
(1) High-temperature and high-humidity test A high-temperature and high-humidity test was performed in which the sample was left for 1000 hours in an environment of 80 ° C and relative humidity of 90%, and the state of the plated film after the test was visually observed. The result of visual observation was evaluated according to the following evaluation criteria. The results are shown in Table 1.

Evaluation criteria for high temperature and high humidity test:
○: There is no peeling, film swelling, or cracking in the plating film ×: There is peeling, film swelling, or cracking in the plating film

(2) Measurement of adhesion strength Using a tensile tester (manufactured by Shimadzu Corp., AGS-100N), in accordance with JIS H8630, under the conditions of an angle of 90 ° and a speed of 25 mm / min over a length of 100 mm on the sample surface, The force when peeling the plating film from the sample was measured. This result was taken as the initial adhesion strength. The results are shown in Table 1. In addition, the sample was allowed to stand in an environment of 80 ° C. and 90% relative humidity as in the high-temperature and high-humidity test described above, and the adhesion strength after 250 hours, 500 hours, 750 hours, and 1000 hours was measured in the same manner. . The results are shown in FIG.

[Example 2]
In Example 2, a molded body (sample) having a plating film was produced by the same method as in Example 1 except that the plating pretreatment was performed using 1.5 mol / L phosphoric acid. did. The obtained sample was subjected to a high temperature and high humidity test and an adhesion strength measurement in the same manner as in Example 1. The results are shown in Table 1 and FIG.

[Comparative Example 1]
In Comparative Example 1, a molded body (sample) having a plating film was produced by the same method as in Example 1 except that the plating pretreatment was performed using 3.0 mol / L hydrochloric acid. . The obtained sample was subjected to a high temperature and high humidity test and an adhesion strength measurement in the same manner as in Example 1. The results are shown in Table 1 and FIG.

[Comparative Example 2]
In Comparative Example 2, a molded body (sample) having a plating film was produced by the same method as in Example 1 except that the plating pretreatment was performed using 3.0 mol / L nitric acid. . The obtained sample was subjected to a high temperature and high humidity test and an adhesion strength measurement in the same manner as in Example 1. The results are shown in Table 1 and FIG.

  As shown in Table 1 and FIG. 5, the plating films of Example 1 using acetic acid for plating pretreatment and Example 2 using phosphoric acid have high initial adhesion strength and are left in a high temperature and high humidity environment. Even after that, the adhesion strength did not decrease. Further, after the high-temperature and high-humidity test, appearance defects such as peeling of the plating film, film swelling, and cracking did not occur.

  On the other hand, the plating films of Comparative Example 1 using hydrochloric acid for plating pretreatment and Comparative Example 2 using nitric acid had initial adhesion strengths equivalent to those of Examples 1 and 2, but in a high temperature and high humidity environment. After standing, the adhesion strength decreased. Further, after the high temperature and high humidity test, appearance defects such as peeling of the plating film, film swelling, or cracking occurred.

  Further, in Comparative Examples 1 and 2, corrosion (rust) was observed on the plated film after the high-temperature and high-humidity test, and corrosion (embrittlement) was also observed on the surface of the formed body on which the plated film was formed. This is presumably because the hydrochloric acid or nitric acid used in the pretreatment for plating remained on the surface or inside of the molded product even though it was washed with pure water. Since the remaining acid gradually corroded the plating film and the surface of the molded body in a high temperature and high humidity environment, the adhesion strength of the plating film was lowered, and it was estimated that appearance defects such as peeling, film swelling and cracking occurred.

  On the other hand, in Examples 1 and 2, it is considered that the acid used in the pretreatment for plating remains on the surface or inside of the molded body. However, since it is a weak acid, the plated film and molded body are left after being left in a high temperature and high humidity environment. It is presumed that it did not affect. From these results, it was confirmed that the molded bodies of Examples 1 and 2 had high adhesion strength as an initial characteristic, and also had durability and reliability over a long period of time. Furthermore, in Example 1 and Example 2, since the acid used for the plating pretreatment is a weak acid, the operator's risk is reduced as compared with a strong acid, and the workability is improved.

[Example 3]
In this example, the same as Example 1 except that nylon 6 (Toyobo, mineral reinforced resin T777-02) mixed with 40 vol% of a mineral containing calcium oxide and silicon dioxide was used as the polyamide resin used in the molded body. Using this material, a molded body (sample) having a plating film was manufactured by the same method.

The surface of the nickel phosphorous plating film of the sample is visually observed, the number of unplated portions present on the entire surface of the sample is counted and averaged, and the number of unplated portions per unit area (cm ² ) is obtained. It was. The results are shown in Table 2. The surface of the nickel phosphorus plating film was observed with a laser microscope. A laser micrograph is shown in FIG.

[Comparative Example 3]
In this comparative example, a molded body (sample) having a plating film was manufactured by the same method as in Example 3 except that the plating pretreatment was performed using 3.0 mol / L hydrochloric acid. .

In the same manner as in Example 3, the surface of the nickel phosphorous plating film of the sample was visually observed, and the number of unplated portions per unit area (cm ² ) was determined. The results are shown in Table 2. The surface of the nickel phosphorus plating film was observed with a laser microscope. A laser micrograph is shown in FIG. Further, the cross section near the unplated portion of the sample was observed with an SEM (scanning electron microscope). A SEM photograph is shown in FIG.

  As shown in Table 2, the sample of Example 3 in which acetic acid was used for the plating pretreatment had almost no unplated portion that could be visually confirmed. As shown in FIG. 6A, the unattached portion confirmed by the laser microscope observation was as small as 100 μm or less, and the appearance was not defective.

  On the other hand, in the sample of Comparative Example 3 in which hydrochloric acid was used for the pretreatment for plating, many unplated portions that could be visually confirmed were observed. As shown in FIG. 6 (b), the size of the unattached portion was also larger than that of the unattached portion of Example 3 shown in FIG. 6 (a).

  Comparing the plating film formation area and the unplated portion in the sample of Comparative Example 3, as shown in FIG. 7, in the plating film formation area 501, a metal area made of polyamide resin and nickel phosphorus is formed in the vicinity of the molded body surface. The mixed layer 503 was formed, and the nickel phosphorus plating film 504 was grown on the mixed layer 503. On the other hand, in the plating non-attached portion 502, nickel phosphorus particles are deposited on the surface of the molded body, but no plating film has been formed, and a polyamide resin and a metal are formed near the surface of the molded body. A mixed layer with the region was not observed.

  In Comparative Example 3, the cause of the occurrence of such an unplated portion is not clear, but by using a strong acid such as hydrochloric acid for the plating pretreatment, the strong acid and the mineral contained in the molded body react to generate gas. It is speculated that a phenomenon that adversely affects some plating reaction occurs. In Example 3, by using acetic acid, which is a weak acid, for plating pretreatment, no plating non-adhered portion was generated on the molded body made of polyamide resin mixed with minerals, and the appearance characteristics were excellent. It was confirmed that a plating film can be formed.

  As mentioned above, although the manufacturing method of the molded object which has a plating film of this invention has been concretely demonstrated by the Example, this invention is not limited to these Examples. For example, in Examples 1 to 3, acetic acid and phosphoric acid were used for the plating pretreatment, but other acids such as formic acid, butyric acid, lauric acid, lactic acid, malic acid, citric acid, oleic acid, linoleic acid, Even with carboxylic acids such as benzoic acid, oxalic acid, succinic acid, malonic acid, maleic acid, tartaric acid, amino acids, etc., and weak acids in this specification such as boric acid, hypochlorous acid, hydrogen fluoride, hydrogen sulfide, etc. It is presumed that the same effect is produced. In Example 3, a polyamide resin containing calcium oxide and silicon dioxide was used as a mineral. However, silicates such as calcium silicate, aluminum silicate, and magnesium silicate, calcium carbonate, magnesium oxide, and hydroxide It is presumed that the same effect can be obtained even when a polyamide resin containing at least one mineral selected from the group consisting of magnesium, barium sulfate, and a compound (ore) containing these is used.

  The method for producing a molded body having a plated film according to the present invention has a high adhesion strength as an initial characteristic, a durability and reliability over a long period of time, and a molded body having an excellent appearance characteristic. Can be manufactured. Therefore, the molded body having a plated film manufactured according to the present invention can be used for decorative purposes that require high durability.

1000 Molding Machine 100 Pressurized Fluid Supply Device 250 Clamping Unit 200 Kneading Device 210 Plasticizing Cylinder 20 Screw S1 Upstream Seal Mechanism S2 Downstream Seal Mechanism 501 Plating Film Forming Area 502 Unplated Part 503 Made of Polyamide Resin and Nickel Phosphorus Mixed layer 504 with metal region Nickel phosphorus plating film

Claims (9)

A method for producing a molded body having a plating film,
Preparing a molded body made of a polyamide resin containing fine metal particles;
Bringing a weak acid into contact with the molded article;
The manufacturing method of the molded object which has a plating film including forming the plating film | membrane by making an electroless plating liquid contact the said molded object which contacted the said weak acid.   The method for producing a molded body having a plated film according to claim 1, wherein the weak acid is an acid that dissolves a polyamide resin.   The weak acid is acetic acid, formic acid, butyric acid, lauric acid, lactic acid, malic acid, citric acid, oleic acid, linoleic acid, benzoic acid, oxalic acid, succinic acid, malonic acid, maleic acid, tartaric acid, phosphoric acid, boric acid, The method for producing a molded body having a plating film according to claim 1 or 2, which is a kind selected from the group consisting of hypochlorous acid, hydrogen fluoride, and hydrogen sulfide.   The method for producing a molded body having a plating film according to claim 3, wherein the weak acid is acetic acid or phosphoric acid.   The said polyamide resin is nylon, The manufacturing method of the molded object which has a plating film as described in any one of Claims 1-4.   The manufacturing method of the molded object which has a plating film as described in any one of Claims 1-5 in which the said molded object contains a mineral further.   The mineral is at least one selected from the group consisting of calcium silicate, aluminum silicate, magnesium silicate, silicon dioxide, calcium oxide, calcium carbonate, magnesium oxide, magnesium hydroxide, barium sulfate and compounds containing these. The manufacturing method of the molded object which has a plating film of Claim 6.   The manufacturing method of the molded object which has a plating film as described in any one of Claims 1-7 in which the said metal microparticle contains palladium. Preparing the molded body,
Dissolving or dispersing the metal fine particles in pressurized carbon dioxide;
The plating according to any one of claims 1 to 8, wherein the molded body is manufactured by a method of manufacturing a molded body including bringing the pressurized carbon dioxide in which the metal fine particles are dissolved into contact with the polyamide resin. The manufacturing method of the molded object which has a film | membrane.

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