Plating primer and plated products

Abstract

To provide plating primer paint which can form a fine pattern, maintain plating deposition properties, and suppress plating thickening with time, and a plated body which has an electroless metal plating film using the plating primer paint.SOLUTION: There is provided primer paint capable of forming a metal plating film in an electroless plating method, and the plating primer paint includes electrically conductive or reducible polymer fine particles, synthetic resin, and an inorganic filler, wherein the synthetic resin is epoxy resin of 875 to 9,200 in epoxy equivalent, and the inorganic filler is hydrophilic. The mass ratio of the synthetic resin and the inorganic filler is 1:0.3 to 1.0, and a binder is a combination of the synthetic resin and the inorganic filler, the mass ratio of the reducible or electrically conductive polymer fine particles and the binder is 1:12 to 60.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an electrodeposition primer paint and an electroplated article in which a metal plating film is provided on a substrate by electroless plating using the electrodeposition primer paint.

Background Art

[0002] As an electrodeposition primer paint, those containing conductive or reducing polymer fine particles, a synthetic resin, and an inorganic filler are known. After such an electrodeposition primer paint is applied to a substrate in a full-surface or pattern shape and dried to form an electrodeposition primer layer, a catalytic metal such as palladium is reduced and adsorbed on the conductive or reducing polymer fine particles in the electrodeposition primer layer, and then, by subjecting the catalytic metal to electroless plating, a metal plating film can be formed on the electrodeposition primer layer.

[0003] Electroplated articles with a metal plating film formed on a substrate are used in applications such as electromagnetic shielding materials, transparent conductive films used in touch panels, and printed wiring boards.

[0004] By the way, in a process of heat-treating the electroplated article, such as in solder reflow when mounting semiconductor components on the electroplated article, if the heat resistance of the electroplated article is poor, there has been a problem that peeling between the substrate and the metal plating film occurs after the heat treatment.

[0005] In response to this problem, the present applicant has developed an electrodeposition primer paint having excellent heat resistance by using an epoxy resin having a specific epoxy equivalent as a synthetic resin, and has already filed a patent application (Patent Document 1). If the electrodeposition primer paint of Patent Document 1 is used, the epoxy resin is sufficiently crosslinked to form a tough and highly barrier coating film layer, so it has been found that an electroplated article having high adhesion between the substrate and the metal plating film can be obtained even when exposed to a high-temperature environment.

[0006] Furthermore, it is generally known that inorganic fillers are added to paints to adjust their viscosity to a level suitable for various printing methods. In the case of the plating primer described in Patent Document 1, even without the addition of inorganic fillers, it was sufficient to form fine line patterns with a line width exceeding 100 μm. However, for fine patterns with a line width of 100 μm or less, which are required in fields such as printed electronics (PE), the paint would bleed, and improvement was needed. In addition, in the PE (polyethylene) field, the demand for miniaturization of metal plating films is increasing. This is because finer patterns increase pattern density, enabling smaller devices and higher performance by reducing the mounting area. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2020-158728 [Overview of the project] [Problems that the invention aims to solve]

[0008] When epoxy resin is used as the synthetic resin in a plating primer, a hydrophobic inorganic filler is generally used to adjust the viscosity. This paint containing an inorganic filler exhibits thixotropy (thixo property), meaning that its viscosity decreases when shear stress is continuously applied, but returns to its original viscosity after being left for a certain period of time. However, in the applicant's research, it was found that the deposition performance of metal plating films by electroless plating was poor in plating underlayers formed with plating undercoats using hydrophobic inorganic fillers. This is thought to be because the surface of the plating underlayer becomes hydrophobic, reducing the adsorption capacity of the catalyst metal. On the other hand, one method to increase the amount of conductive or reducing polymer fine particles added is to increase the amount of catalytic metal adsorbed, but this can cause the polymer fine particles to aggregate in the paint, potentially increasing the viscosity over time.

[0009] Therefore, the applicant attempted to adjust the viscosity of the epoxy resin using a hydrophilic inorganic filler. As a result, the surface of the plating underlayer formed by the plating undercoat paint became hydrophilic, increasing the adsorption of the catalyst metal, and thus a metal plating film was deposited on the plating underlayer by electroless plating. However, it was found that the interaction between the epoxy groups in the plating primer and the hydrophilic groups of the inorganic filler impairs the thixotropy of the paint, causing its viscosity to increase over time (thickening). This phenomenon is particularly noticeable in the printing process, and possible causes include shear during printing or solvent evaporation due to prolonged printing. Therefore, there is a need for the development of coatings that can reliably print continuous fine patterns.

[0010] The present invention aims to provide a plating undercoat paint that can form a fine pattern, maintain plating deposition properties, and suppress viscosity increase over time, and a plated product obtained by applying a metal plating film to a substrate using the plating undercoat paint by electroless plating. [Means for solving the problem]

[0011] The present invention relates to a plating primer capable of forming a metal plating film by an electroless plating method, The aforementioned plating primer contains conductive or reducing polymer fine particles, synthetic resin, and inorganic filler. The aforementioned synthetic resin is an epoxy resin having an epoxy equivalent weight of 875 to 9200. The inorganic filler has hydrophilic properties. The average primary particle size of the inorganic filler is 1 nm to 5 μm. The mass ratio of the synthetic resin to the inorganic filler is synthetic resin:inorganic filler = 1:0.3~1.0. When the aforementioned synthetic resin and the aforementioned inorganic filler are combined to form a binder, the mass ratio of reducing or conductive polymer fine particles to the binder is: polymer fine particles:binder = 1: 12~18 It is characterized by being such.

[0012] This invention makes it possible to maintain plating deposition properties and suppress viscosity increase over time, even when using hydrophilic inorganic fillers, by specifying the mass ratio of the inorganic filler to the synthetic resin, and the binder formed by combining the inorganic filler and the synthetic resin, to polymer fine particles.

[0013] Furthermore, the present invention also includes plated products in which a plating underlayer made of the plating undercoat paint is provided on a substrate, and a metal plating film is provided on the plating underlayer by an electroless plating method. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a plating primer that can form fine patterns, maintain plating deposition properties, and suppress viscosity increase over time. Furthermore, the present invention provides plated products in which a metal plating film is provided on a substrate by electroless plating using the plating undercoat paint of the present invention. [Modes for carrying out the invention]

[0015] The present invention relates to a plating primer capable of forming a metal plating film by electroless plating, wherein the plating primer comprises conductive or reducing polymer fine particles, a synthetic resin, and an inorganic filler.

[0016] The reducing polymer fine particles of the present invention are not particularly limited as long as they are polymers having π-conjugated double bonds and an electrical conductivity of less than 0.01 S / cm, preferably 0.005 S / cm or less. Examples include polyacetylene, polyacene, poly(p-phenylene), poly(p-phenylene vinylene), polypyrrole, polyaniline, polythiophene, and various derivatives thereof, with polypyrrole being preferred. Reducing polymer nanoparticles can be synthesized from monomers containing π-conjugated double bonds, but commercially available reducing polymer nanoparticles can also be used. The reducing polymer microparticles are used as a dispersion liquid dispersed in an organic solvent. In order to maintain the dispersion stability in the dispersion liquid, the solid content is set to 16% by mass or less (solid content ratio) of the mass of the dispersion liquid. Examples of the organic solvent for dispersing the reducing polymer microparticles include aliphatic esters such as butyl acetate, aromatic solvents such as toluene, ketones such as methyl ethyl ketone, cyclic saturated hydrocarbons such as cyclohexane, linear saturated hydrocarbons such as n-octane, linear saturated alcohols such as methanol, ethanol, and n-octanol, aromatic esters such as methyl benzoate, aliphatic ethers such as diethyl ether, and mixtures thereof.

[0017] The conductive polymer microparticles of the present invention are not particularly limited as long as they are polymers having a conductive π-conjugated double bond. Examples thereof include polyacetylene, polyacene, polyphenylene, polyphenylene vinylene, polypyrrole, polyaniline, polythiophene, and various derivatives thereof, and preferably polypyrrole. The conductive polymer microparticles can be synthesized and used from monomers having a π-conjugated double bond, or commercially available conductive polymer microparticles can also be used. The conductive polymer microparticles are used as a dispersion liquid dispersed in an organic solvent. In order to maintain the dispersion stability in the dispersion liquid, the solid content is set to 16% by mass or less (solid content ratio) of the mass of the dispersion liquid. As the organic solvent for dispersing the conductive polymer microparticles, the same solvents as those for dispersing the reducing polymer microparticles can be used.

[0018] The synthetic resin of the present invention is an epoxy resin having an epoxy equivalent of 875 to 9200. As the epoxy resin, any resin having two or more epoxy groups in the molecule can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, phenol aralkyl type epoxy resin, biphenyl type epoxy resin, triphenylmethane type epoxy resin, dicyclopentadiene type epoxy resin, epoxy resins modified from these resins, and various other epoxy resins can be used. These can be used alone or as a mixture of two or more types.

[0019] In addition, in the case of an epoxy resin with an epoxy equivalent less than 875, it becomes difficult for the catalytic metal to adsorb, and as a result, it is difficult to obtain a metal plating film, that is, the plating deposition property is poor. In addition, even if a metal plating film is obtained, in the case of polypyrrole fine particles and an epoxy resin with an epoxy equivalent less than 875, the crosslinking of the epoxy resin tends to be insufficient. When exposed to a high-temperature environment, oxidized copper (copper oxide) and copper diffuse through the coating film layer and reach the substrate. It is presumed that a high adhesion, specifically, a 180-degree peel strength of 0.35 N / mm or more cannot be obtained. In the case of an epoxy resin with an epoxy equivalent exceeding 9200, there is no decrease in adhesion when exposed to a high-temperature environment, but there is a possibility that it cannot be made into a paint. Here, the equivalent means the molecular weight (Mw) divided by the number of functional groups (n), which means equivalent [g / eq] = Mw / n.

[0020] As the inorganic filler of the present invention, powders of metal oxides such as titanium oxide (titania), aluminum oxide (alumina), and silicon oxide (silica) can be used, and they have hydrophilicity. Generally, inorganic fillers of metal oxides often have hydrophilic groups on their surface and exhibit hydrophilicity. When almost all of these hydrophilic groups are replaced with hydrophobic groups such as alkyl groups or amino groups through surface hydrophobic treatment, they are called hydrophobic inorganic fillers and are distinguished from hydrophilic inorganic fillers that have not undergone surface hydrophobic treatment. Therefore, the hydrophilic inorganic filler of the present invention is one that has not undergone surface hydrophobic treatment. However, if the effects of the present invention are not impaired, a mixture of hydrophilic and hydrophobic inorganic fillers may be used. Silica particles are particularly preferred because they contain many hydrophilic groups and their particle size can be easily adjusted. This is because a high proportion of hydrophilic groups on the surface of the plating underlayer increases the amount of catalyst metal adsorbed, resulting in excellent plating deposition performance.

[0021] In the present invention, the average primary particle size of the inorganic filler is preferably 1 nm to 5 μm, and more preferably 1 nm to 1 μm. The smaller the average primary particle size of the inorganic filler, i.e., the larger its specific surface area, the greater the surface area of ​​the coating film, which in turn increases the amount of catalyst metal adsorbed, thereby improving plating deposition performance. However, when the average primary particle size is less than 1 nm, even a small amount of additive can increase the filler density in the paint and easily increase the initial viscosity of the paint. However, a certain amount of additive is necessary to improve the plating deposition properties, and if that is done, the viscosity will increase too much, making printing itself difficult. Furthermore, when the average primary particle diameter exceeds 1 μm, the proportion of paint in contact with the filler surface decreases, resulting in insufficient swelling of the filler and a tendency for the initial viscosity of the paint to not increase easily. Therefore, it becomes difficult to adjust the viscosity to suit various printing methods, making the printing of fine patterns even more challenging. The average primary particle diameter is calculated by taking images of inorganic particles at 50,000x magnification using a typical scanning electron microscope, then randomly measuring the diameters of 50 or more inorganic particles in the resulting images and calculating the average.

[0022] In the plating primer of the present invention, the mass ratio of synthetic resin to inorganic filler is synthetic resin:inorganic filler = 1:0.3 to 1.0. If the amount of inorganic filler exceeds 1.0 part by mass per 1 part by mass of synthetic resin, the self-aggregation of the inorganic filler is promoted due to the interaction between the epoxy groups and the hydrophilic groups of the inorganic filler, making it difficult to suppress the thickening over time. Furthermore, if the amount of inorganic filler is less than 0.3 parts by mass, the surface area of ​​the coating film does not increase, resulting in insufficient effect in increasing the adsorption amount of the catalyst metal and a decrease in plating deposition performance.

[0023] In the plating primer of the present invention, when a binder is made by combining a synthetic resin and an inorganic filler, the mass ratio of reducing or conductive polymer fine particles to the binder is polymer fine particles:binder = 1:12 to 60. If the amount of binder exceeds 60 parts by mass per 1 part by mass of reducing or conductive polymer fine particles, the proportion of reducing or conductive polymer fine particles to which the catalyst metal can adhere decreases, resulting in a decrease in plating deposition performance. Furthermore, if the binder content is less than 12 parts by mass, the self-aggregation of reducing or conductive polymer fine particles in the paint is promoted, making it difficult to suppress thickening over time. In addition, the crosslinking of the epoxy resin becomes insufficient, and delamination between the substrate and the metal plating film is likely to occur even when exposed to high-temperature environments. Furthermore, from the viewpoint of plating deposition rate, the binder should be 12 to 18 parts by mass. below It is preferable that this be the case.

[0024] The plating primer of the present invention may contain conductive or reducing polymer fine particles, a synthetic resin, an inorganic filler, and a solvent. The solvent used is not particularly limited as long as it can dissolve the synthetic resin, but solvents that dissolve the substrate extensively are undesirable. However, even solvents that dissolve the substrate extensively can be used by mixing them with other less soluble solvents to reduce their solubility. Examples of the solvents mentioned above include aliphatic esters such as butyl acetate, aromatic solvents such as toluene and benzyl alcohol, ketones such as methyl ethyl ketone, cyclic saturated hydrocarbons such as cyclohexane, linear saturated hydrocarbons such as n-octane, linear saturated alcohols such as methanol, ethanol, and n-octanol, aromatic esters such as methyl benzoate, aliphatic ethers such as diethyl ether, and mixtures thereof. Furthermore, when mixing synthetic resin and inorganic fillers into a dispersion of polymer fine particles dispersed in an organic solvent, the organic solvent used in the dispersion can be used as part or all of the solvent for the plating primer.

[0025] Depending on the application and the object to be coated, the plating primer of the present invention may contain, for example, resins such as dispersion stabilizers, thickeners, and ink binders. Furthermore, inorganic fillers other than the inorganic fillers of the present invention, such as carbon black, may be added, as long as they do not impair the effects of the present invention.

[0026] The plating primer of the present invention can be obtained, for example, by adding a binder, which is a pre-mixed mixture of synthetic resin and inorganic filler, to a dispersion of conductive or reducing polymer fine particles, thereby obtaining a plating primer in which the solid components are uniformly dispersed without aggregation.

[0027] The plating undercoat of the present invention can be applied to a substrate either entirely or in a pattern, and then dried and cured by, for example, heating or irradiation with light or electron beams to form a plating undercoat layer either entirely or in a pattern. The drying conditions are not particularly limited and can be carried out at room temperature or under heated conditions. When heating, it is preferable to use a temperature lower than the Tg of the substrate.

[0028] The method for applying the plating primer of the present invention to a substrate is not particularly limited, and can be used, for example, by printing or coating using a screen printing machine, gravure printing machine, flexographic printing machine, offset printing machine, spin coater, roll coater, etc. Among these, screen printing machines, gravure offset printing machines, flexographic printing machines, and roll coaters are preferred for forming fine patterns with a line width of 100 μm or less. Furthermore, from the viewpoint of continuous printability, a viscosity increase rate of 100% or more and less than 200% is preferable, and less than 100% is more preferable.

[0029] Furthermore, the thickness of the plated underlayer formed is preferably 10 nm to 10 μm (0.01 to 10 μm), and more preferably 1.0 μm to 10 μm. If the thickness is less than 10 nm, plating will be difficult to deposit. Furthermore, if the thickness exceeds 10 μm, it becomes difficult to achieve good adhesion between the substrate and the metal plating film. Furthermore, setting the particle size to a range of 1.0 μm to 10 μm improves the deposition properties of the plating.

[0030] The substrate of the present invention is not particularly limited, but examples include polyethylene naphthalate (PEN) resin, polypropylene (PP) resin, polycarbonate (PC) resin, polyamide (PA) resin, polyimide (PI) resin, cycloolefin polymer (COP) resin, polyetheretherketone (PEEK) resin, liquid crystal polymer (LCP) resin, fluororesin, epoxy resin, phenolic resin, glass, and the like. Furthermore, the shape of the substrate is not particularly limited, but examples include a plate or a film. Other examples of base materials include resin molded products formed by injection molding or other methods. By applying the plated material of the present invention to these resin molded products, decorative plated products for automobiles can be created, for example. Alternatively, by applying the plated material of the present invention to a film made of polyimide resin, either entirely or in a pattern, electrical circuit components can be created, for example. Polyimide (PI) resin film and liquid crystal polymer (LCP) resin film are preferred as substrates for use in the present invention.

[0031] As described above, a plated product of the present invention is obtained by providing a base layer made of the plating undercoat paint of the present invention on a substrate, and providing a metal plating film on the plating undercoat layer by an electroless plating method. In other words, a plated product can be obtained by immersing a substrate on which a plating underlayer has been formed in a catalyst solution for depositing a catalyst metal such as palladium chloride, then washing it with water, and finally immersing it in an electroless plating bath.

[0032] The catalyst solution is a solution containing a noble metal (catalyst metal) that has catalytic activity for electroless plating. Examples of catalyst metals include palladium, gold, platinum, and rhodium. These metals may be in elemental form or compound form. Palladium compounds are preferred from the viewpoint of stability, and among them, palladium chloride is particularly preferred. A preferred specific catalyst solution is a 0.05% palladium chloride-0.005% hydrochloric acid aqueous solution (pH 3). The processing temperature is 20 to 50°C, preferably 30 to 40°C, and the processing time is 0.1 to 20 minutes, preferably 1 to 10 minutes. Through the above procedure, the polymer microparticles in the plating substrate ultimately become conductive polymer microparticles.

[0033] The substrate treated as described above is immersed in a plating solution to deposit metal, thereby forming an electroless plating film. The plating solution is not particularly limited as long as it is a plating solution typically used for electroless plating. In other words, all metals that can be used for electroless plating, such as copper, gold, silver, and nickel, can be applied, but copper is preferred. Specific examples of electroless copper plating baths include, for instance, the ATS Adcopper IW bath (manufactured by Okuno Pharmaceutical Co., Ltd.). The processing temperature is 20 to 50°C, preferably 30 to 40°C, and the processing time is 1 to 30 minutes, preferably 5 to 15 minutes. The resulting plated product is preferably cured for several hours or more, for example, two hours or more, at a temperature range lower than the Tg of the substrate used.

[0034] Furthermore, in the case of a plating undercoat formed by applying a plating undercoat paint containing conductive polymer fine particles to a substrate, a dedoping treatment can be performed afterward, and then the plated product can be manufactured by the same operation as described above. As a dedoping treatment, a method is used in which a substrate having a plating underlayer containing conductive polypyrrole fine particles and a binder is immersed in a solution containing a reducing agent, such as boron hydride compounds such as sodium borohydride and potassium borohydride, alkylamine boranes such as dimethylamine borane, diethylamine borane, trimethylamine borane, and triethylamine borane, and hydrazine, or in an alkaline solution. From the viewpoint of operability and economics, immersion treatment with an alkaline solution is preferred. In particular, since the plating underlayer containing conductive polymer microparticles, synthetic resin, and inorganic fillers can be made thin, dedoping can be achieved by short-time alkali treatment under mild conditions. For example, the sample is treated in a 1M aqueous sodium hydroxide solution at a temperature of 20 to 50°C, preferably 30 to 40°C, for 1 to 30 minutes, preferably 3 to 10 minutes. The substrate, which has undergone dedoping treatment as described above and has a plating underlayer formed on it, is plated by electroless plating, and this electroless plating can be carried out by the same operation as described above.

[0035] As described above, a plated product is manufactured in which a plating underlayer is formed on the surface of the substrate, and a metal plating film is formed on the plating underlayer by electroless plating. Furthermore, the plated object described above can be further plated with the same or a different metal by electroplating on the formed metal plating film. Furthermore, the metal plating film may be formed on both sides of the substrate.

[0036] The present invention provides a plating primer that can form fine patterns, maintain plating deposition properties, and suppress viscosity increase over time.

[0037] Here, the plating primer of the present invention is evaluated based on its printability, viscosity, and plating deposition properties, as shown below.

[0038] [Printability] Using a screen printing machine, the plating undercoat paint of the present invention is applied to a substrate using a stencil that forms a straight pattern with L / S = 100 μm / 100 μm. The substrate is then heated in a 140°C oven for 30 minutes to dry and harden, forming a patterned plating undercoat layer on the substrate. The fine lines of the plating undercoat layer are observed at 50x magnification using a digital microscope (manufactured by Keyence Corporation, product name "VHX-500"), and the line width is measured between two points. The printability is evaluated as follows based on this value. ◎ Line width within 100 ± 20 μm × Line width exceeds 100 ± 20 μm

[0039] [Thickening properties] The viscosity of the plating undercoat paint of the present invention immediately after preparation is measured using a digital viscometer (manufactured by Eiko Seiki Co., Ltd., product name "DV2T"). At this time, the spindle used is "SC4-28", and the viscosity after stirring at a rotation speed of 14 rpm for 10 minutes is defined as the initial viscosity A. Next, 30g of paint is spread evenly over a PET film substrate (Toyobo Co., Ltd., "A4300") cut to a size of 300mm in length and 500mm in width using a bar coater, and left to stand for 2 hours at room temperature and humidity. After that, the paint on the substrate is collected and its viscosity is measured in the same way as the initial viscosity A, and this is defined as the viscosity over time B. The viscosity increase rate is calculated using the formula: (B / A-1)×100, and the viscosity-increasing properties are evaluated as follows based on this value. ◎ Viscosity increase rate is less than 100% ○ Viscosity increase rate of 100% or more and 200% or less × Viscosity increase rate exceeds 200%

[0040] [Plating deposition properties] A substrate with a 2.0 μm thick plating underlayer is immersed in a 1 M sodium hydroxide aqueous solution at 35°C for 5 minutes, if necessary, then rinsed with deionized water. Next, it is immersed in a 0.02% palladium chloride - 0.01% hydrochloric acid aqueous solution at 35°C for 5 minutes, then rinsed with deionized water to deposit the catalyst metal onto the plating underlayer. Subsequently, it is immersed in an electroless plating bath (manufactured by Okuno Pharmaceutical Industry Co., Ltd., product name "ATS Adcopper IW Bath") at 35°C for 10 minutes to deposit copper with a thickness of 0.3 μm. At this time, the area where copper is deposited is observed visually, and the plating deposition performance is evaluated as follows. ◎ After 5 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the underlying layer. ○ After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the underlying layer. × After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), there are areas in the underlayer where the plating film has not grown.

[0041] The plating undercoat of the present invention has an overall rating of ◎ when all three properties—printability, viscosity, and plating deposition—are rated ◎, and an overall rating of ○ when any one of the three properties—printability, viscosity, or plating deposition—is rated ○. It allows for the formation of fine patterns, maintains plating deposition properties, and suppresses viscosity over time. Therefore, it enables the stable and continuous printing of fine patterns, and is expected to contribute to the miniaturization and performance improvement of devices in the field of printed electronics.

[0042] The present invention will be described based on embodiments, but is not limited thereto.

[0043] [Dispersion of conductive polymer microparticles] 1.5 mmol of the anionic surfactant Perex OT-P (manufactured by Kao Corporation), 10 mL of toluene, and 100 mL of deionized water were added and stirred at 20°C until emulsified to obtain an emulsion. Next, 21.2 mmol of pyrrole monomer was added to the resulting emulsion and stirred for 1 hour. Then, 6 mmol of ammonium persulfate was added and the polymerization reaction was carried out for 2 hours. After the reaction was complete, the organic phase was collected and washed several times with deionized water to obtain conductive polypyrrole fine particles dispersed in toluene. At this time, the solid content ratio in the dispersion was 10% by mass.

[0044] [Examples 1-3, Comparative Examples 1-3] A conductive polypyrrole microparticle dispersion, epoxy resin (epoxy equivalent 3000-5000), and hydrophilic inorganic filler A (silica without surface hydrophobic treatment, average primary particle diameter 1 μm or less) were mixed in the mass ratios shown in Table 1. A solvent (benzyl alcohol) was added to adjust the solid content ratio (final solid content ratio) of the conductive polypyrrole microparticles, epoxy resin, and hydrophilic inorganic filler A combined to 29% by mass in the paint, thereby obtaining a plating primer. At this time, a binder, which was previously mixed with epoxy resin and inorganic filler A, was mixed with the conductive polypyrrole microparticle dispersion. The mass ratio of conductive polypyrrole microparticles to the binder (combined epoxy resin and inorganic filler A) was fixed at conductive polypyrrole microparticles:binder = 1:16, and the mass ratio of epoxy resin and inorganic filler A in the binder was changed.

[0045] [Examples 4-6, Comparative Examples 4, 5] A conductive polypyrrole microparticle dispersion, epoxy resin (epoxy equivalent 3000-5000), and hydrophilic inorganic filler A (silica without surface hydrophobic treatment, average primary particle diameter 1 μm or less) were mixed in the mass ratios shown in Table 2. A solvent (benzyl alcohol) was added to adjust the solid content ratio (final solid content ratio) of the conductive polypyrrole microparticles, epoxy resin, and hydrophilic inorganic filler A combined to 29% by mass in the paint, thereby obtaining a plating primer. At this time, a binder, which was previously mixed with epoxy resin and inorganic filler A, was mixed with the conductive polypyrrole microparticle dispersion. The mass ratio of epoxy resin to inorganic filler A in the binder was fixed at epoxy resin:inorganic filler A = 1:0.3, and the mass ratio of conductive polypyrrole microparticles to the binder (combined epoxy resin and inorganic filler A) was changed.

[0046] [Example 7] A plating primer was obtained in the same manner as in Example 1, except that hydrophilic inorganic filler A was replaced with hydrophilic inorganic filler B (silica that has not undergone surface hydrophobic treatment, with an average primary particle size of 12 nm).

[0047] [Example 8] A plating primer was obtained in the same manner as in Example 1, except that hydrophilic inorganic filler A was replaced with hydrophilic inorganic filler C (silica that has not undergone surface hydrophobic treatment, with an average primary particle size of 7 nm).

[0048] [Comparative Example 6] A plating primer was obtained in the same manner as in Example 1, except that the hydrophilic inorganic filler A was replaced with a hydrophobic inorganic filler D (silica in which hydrophilic groups were replaced with dimethylsilyl groups by surface hydrophobic treatment, with an average primary particle size of 12 nm).

[0049] [Comparative Example 7] A plating primer was obtained in the same manner as in Example 1, except that the hydrophilic inorganic filler A was replaced with a hydrophobic inorganic filler E (silica in which the hydrophilic groups were replaced with trimethylsilyl groups by surface hydrophobic treatment, with an average primary particle size of 12 nm).

[0050] [Comparative Example 8] A plating primer was obtained in the same manner as in Example 1, except that the hydrophilic inorganic filler A was replaced with a hydrophobic inorganic filler F (silica in which hydrophilic groups were replaced with dimethylpolysiloxane groups by surface hydrophobic treatment, with an average primary particle size of 12 nm).

[0051] The obtained plating primers were evaluated for printability, viscosity, and plating deposition properties as follows, and the results are shown in Tables 1 to 3. In this invention, a product with a ○ rating in the overall evaluation is considered superior.

[0052] [Printability] Using a screen printing machine, a plating primer was applied to a polyimide film substrate (manufactured by Toray DuPont Ltd., product name "Kapton 200H") cut to a size of 130 mm in length and 270 mm in width, using a stencil that forms a straight pattern with L / S = 100 μm / 100 μm. The substrate was then heated in a 140°C oven for 30 minutes to dry and harden, forming a patterned plating primer layer on the substrate. The fine lines of this plating primer layer were observed at 50x magnification using a digital microscope (manufactured by Keyence Corporation, product name "VHX-500"), and the line width was measured between two points. The printability was evaluated based on these values ​​as follows. ◎ Line width within 100 ± 20 μm × Line width exceeds 100 ± 20 μm

[0053] [Thickening properties] The viscosity of the plating primer paint immediately after preparation was measured using a digital viscometer (manufactured by Eiko Seiki Co., Ltd., product name "DV2T"). The spindle used was "SC4-28," and the viscosity after stirring at a rotation speed of 14 rpm for 10 minutes was defined as the initial viscosity A. Next, 30g of paint was spread evenly over a PET film substrate (Toyobo Co., Ltd., "A4300") cut to a size of 300mm in length and 500mm in width using a bar coater. The substrate was then left to stand at room temperature and humidity for 2 hours. After that, the paint on the substrate was collected and its viscosity was measured in the same way as the initial viscosity A, and this was defined as the viscosity over time B. The viscosity increase rate was calculated using the formula: (B / A-1)×100, and the viscosity-increasing properties were evaluated as follows based on this value. ◎ Viscosity increase rate is less than 100% ○ Viscosity increase rate of 100% or more and 200% or less × Viscosity increase rate exceeds 200%

[0054] [Plating deposition properties; pattern] In the same manner as the evaluation of printability, a plating underlayer with a straight pattern of L / S = 100 μm / 100 μm was formed on a polyimide film substrate (manufactured by Toray DuPont Ltd., product name "Kapton 200H") cut to a size of 130 mm in length and 270 mm in width. At this time, the thickness of the plating underlayer was 2.0 μm. Next, it was immersed in a 1 M sodium hydroxide aqueous solution at 35°C for 5 minutes, then washed with deionized water, and then immersed in a 0.02% palladium chloride - 0.01% hydrochloric acid aqueous solution at 35°C for 5 minutes, then washed with deionized water. Next, it was immersed in an electroless plating bath (manufactured by Okuno Pharmaceutical Co., Ltd., product name "ATS Adcopper IW Bath") at 35°C for 10 minutes to deposit copper with a thickness of 0.3 μm. At this time, the area where copper was deposited was observed visually, and the plating deposition performance was evaluated as follows. ◎ After 5 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the underlying layer. ○ After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the underlying layer. × After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), there are areas in the underlayer where the plating film has not grown.

[0055] [Plating deposition properties; entire surface (solid)] A plating underlayer was formed on the entire surface of a polyimide film substrate (manufactured by Toray DuPont, product name "Kapton 200H") cut to a size of 130 mm in length and 270 mm in width using a screen printing machine. Next, it was immersed in a 1 M sodium hydroxide aqueous solution at 35°C for 5 minutes, then rinsed with deionized water. Then, it was immersed in a 0.02% palladium chloride - 0.01% hydrochloric acid aqueous solution at 35°C for 5 minutes, then rinsed with deionized water. Next, it was immersed in an electroless plating bath (manufactured by Okuno Pharmaceutical Co., Ltd., product name "ATS Adcopper IW Bath") at 35°C for 10 minutes to deposit copper with a film thickness of 0.3 μm. At this time, the area where copper was deposited was measured visually, and the ratio to the area where the plating underlayer was formed (the entire surface) was calculated, and the plating deposition performance was evaluated as follows based on this value. ◎ After 5 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the plating substrate layer. ○ After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), the plating film has grown on the underlying layer. × After 10 minutes of immersion from the start of plating (after impregnation in the electroless plating bath), there are areas in the underlayer where the plating film has not grown.

[0056] 〔comprehensive evaluation〕 If all three properties—printability, viscosity, and plating deposition—received an excellent rating (◎), the overall rating was excellent (◎). If any one of the three properties—printability, viscosity, or plating deposition—received an average rating (〇), the overall rating was good (〇). If any one of the three properties—printability, viscosity, or plating deposition—received an average rating (×), the overall rating was poor (×).

[0057] [Table 1]

[0058] [Table 2]

[0059] [Table 3]

[0060] As shown in Tables 1-3, Examples 1-8 of the present invention yielded a plating undercoat that can form a fine pattern, maintain plating deposition properties, and suppress viscosity increase over time.

[0061] Furthermore, a plated object was obtained in which a plating underlayer made of the plating undercoat paint of the present invention was provided on a substrate, and a metal plating film was provided on the plating underlayer by electroless plating, either covering the entire surface or forming a pattern.

Claims

1. A plating primer capable of forming a metal plating film by electroless plating, The aforementioned plating primer consists of conductive or reducing polymer fine particles, synthetic resin, and inorganic filler. and The aforementioned synthetic resin is an epoxy resin having an epoxy equivalent weight of 875 to 9200. The inorganic filler is hydrophilic, and the average primary particle size of the inorganic filler is 1 nm to 5 μm. The mass ratio of the synthetic resin to the inorganic filler is synthetic resin:inorganic filler = 1:0.3 to 1.

0. A plating primer characterized in that, when the synthetic resin and the inorganic filler are combined to form a binder, the mass ratio of reducing or conductive polymer fine particles to the binder is polymer fine particles:binder = 1:12 to 18.

2. A plated object comprising a base material on which a plating underlayer made of the plating underpaint described in claim 1 is provided, and a metal plating film is provided on the plating underlayer by an electroless plating method.

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