JPH0745717B2 - Pretreatment method for plating of liquid crystalline polyester resin molded products - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pretreatment method for plating a melt-processable polyester (hereinafter simply referred to as “liquid crystalline polyester”) molded article capable of forming an anisotropic melt phase. More specifically, it relates to a pretreatment method for efficiently applying plating to a liquid crystalline polyester resin molded product having excellent heat resistance and molding processability.

[Conventional technology and its problems]

The liquid crystalline polyester is different from generally known thermoplastic polyesters, such as polybutylene terephthalate and polyethylene terephthalate, and is made of a rigid polymer. There is little entanglement, it is oriented in one direction only by receiving a slight shear stress, and it exhibits so-called liquid crystallinity which is crystalline even in a liquid state.

Such a liquid crystalline polyester is a general polyester resin that does not exhibit liquid crystallinity (the polybutylene terephthalate,
It is chemically more stable than polyethylene terephthalate, etc., and the etching solution for surface roughening used for general polyester cannot be applied as it is. Further, even if the surface is roughened, the surface is not sufficiently active with respect to the catalyst solution prepared for plating, and subsequent electroless plating is less likely to adhere to the surface, and a satisfactory method has not been known yet.

[Means for Solving Problems] The present inventors take advantage of thermally beneficial characteristics such as solder resistance of liquid crystalline polyester to chemically activate the surface without impairing physical and chemical properties. As a result of diligent research on the plating pretreatment process that enables the indispensable catalyst adhesion in the plating application process on the resin surface, after dipping in a specific alkaline solution to roughen the surface, a specific surfactant is added. The present invention has been found out that it is possible to uniformly apply the catalyst by treating with an aqueous solution containing the catalyst.

The specific surfactant used in the present invention has one or more cationic functional groups and anionic functional groups at the same time in its molecular structure, and is an amphoteric compound having the following structure. Surfactant, ie 1) carboxybetaine type Belonging to, 2) sulfobetaine type Belonging to 3) Aminocarboxylic acid salt type-N ▲ H ⁺ ₂ ▼
-COO ^- belonging ones, 4) imidazoline derivative type And so on.

More preferably near neutral (weakly acidic) with the following structure
Aminocarboxylate type having a isoelectric point two R-NH- (CH _{2) n}
COOH (R: C _{12 to} C ₁₈ , n = 1 to 2) is desirable.

The reason why the amphoteric surfactant exerts an effective catalyst imparting effect on the liquid crystalline polyester molded product after surface roughening is presumed as follows.

That is, before the surface roughening is performed, the surface of the liquid crystalline polyester has a small surface tension as well as a general resin molded product and has poor water wettability, so that a Pd-Sn colloid catalyst essential for electroless plating is provided. Can not. Even if the surface tension of water is lowered to make the surface hydrophilic by using a surfactant having good water solubility, only the catalyst is temporarily attached to the surface, and it is easily removed. When immersed in a specific alkaline aqueous solution, hydrolysis occurs on the surface of the liquid crystalline polyester, and an active polar group is formed on the surface,
Further, in the case of the liquid crystalline polyester with a filler, the surface tension of the molded product is increased because the surface is roughened, and the surface can be uniformly wet with water. Usually, when the surface becomes hydrophilic in this way, the Pd-Sn colloid, which is a catalyst for stable plating in the acid of the catalyst solution, tends to adhere easily with the help of the polarity of the resin surface. . However, in the case of liquid crystalline polyester, the adsorption of the catalyst is insufficient due to its molecular structure and it is not suitable for plating as it is. When we examined the application of surfactants, we found that nonionic surfactants and anionic surfactants had no effect on improving the adhesive strength of the catalyst, while cationic surfactants worked effectively on the adsorption of the catalyst. Since the liquid crystal polyester does not have a sufficient adsorption force, the plating surface is likely to be patted.

On the other hand, the anionic functional group of the amphoteric surfactant of the present invention is
It is easily adsorbed to the polar groups on the surface of the roughened liquid crystalline polyester, and the adsorbed surfactant easily adsorbs the catalyst because it acts as a cationic surfactant in the acidic catalyst of the catalyst solution. It is presumed that it facilitates adsorption of the catalyst on the resin surface.

Among the amphoteric surfactants, particularly the aminocarboxylic acid salt caused precipitation and adhesion near the isoelectric point, and the above effects were further accelerated, and good results were obtained.

The treatment of the amphoteric surfactant aqueous solution of the present invention may be carried out by, for example, immersing the molded article in the aqueous solution and treating it. In addition to this, other operations such as spraying and coating the aqueous solution may be used. Good.

The alkaline aqueous solution which is the etching treatment liquid in the present invention is an aqueous solution containing an alkali metal hydroxide or an alkaline earth metal hydroxide as a main component, such as sodium hydroxide, potassium hydroxide or lithium hydroxide. It is an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkaline earth metal hydroxide such as strontium hydroxide or barium hydroxide. The preferred alkaline aqueous solution is an aqueous potassium hydroxide solution. The alkaline aqueous solution is an organic solvent which dissolves the surface decomposition product of the liquid crystalline polyester and is soluble in the alkaline aqueous solution, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and isobutyl alcohol, furan compounds such as tetrahydrofuran, and ethylamine. , One or more solvents selected from nitrogen compounds such as dimethylamine, trimethylamine, propylamine, aniline, pyridine and formamide, and aromatic halogenated hydrocarbons such as chlorobenzene and o-dichlorobenzene. However, it can be used as a composite liquid.

Further, when the liquid crystalline polyester molded article is subjected to the etching treatment with such an aqueous solution, the optimum dipping treatment conditions are searched for and selected according to the composition of the etching liquid. Using an aqueous solution of 20 to 60% by weight, at 30 to 80 ° C. for 3 to 120 minutes,
It is preferable to use 40 to 50% by weight aqueous solution of hydroxide at 40 to 60 ° C.
It takes 10 to 30 minutes. As a particularly preferable example of treatment conditions, treatment with an aqueous solution of about 45% by weight of potassium hydroxide at 60 ° C. for about 30 minutes is suitable.

The liquid crystalline polyester molded product used in the present invention, in order to further improve its plateability, an element of Group II of the periodic table and its oxide, sulfate, phosphate, silicate, or aluminum, silicon, tin, It is preferable that an inorganic filler composed of one or more selected from the group consisting of elements of lead, antimony and bismuth and oxides thereof is blended.

Oxides of elements of Group II of the Periodic Table are magnesium oxide,
Compounds such as calcium oxide, barium oxide, zinc oxide, etc., and phosphates are compounds such as magnesium phosphate, calcium phosphate, barium phosphate, zinc phosphate, magnesium pyrophosphate, calcium pyrophosphate, etc. Is a compound such as magnesium sulfate, calcium sulfate, barium sulfate, and silicate is magnesium silicate, calcium silicate, aluminum silicate, kaolin,
Compounds such as talc, clay, diatomaceous earth, and wollastonite, with phosphate being particularly preferred.

In addition to the above inorganic fillers, one or more selected from the group consisting of aluminum, silicon, tin, lead, antimony, bismuth and other amphoteric metal elements, or oxides of these elements are also preferable.

The compounding amount of these inorganic fillers is 0 to 80% by weight, preferably 10 to 70% by weight, based on the total amount of the liquid crystalline polyester resin composition. If these fillers are not mixed, uneven flow marks may occur on the surface of the molded product, and the surface layer of the molded product may easily be peeled off in a thin layer when an adhesive tape is attached to the surface and peeled off. In addition, the surface-treated portion is likely to cause uneven etching. On the other hand, when it exceeds 80% by weight, the fluidity of the resin is lowered, a molded article having a good surface cannot be obtained, and the surface of the molded article is roughened by etching, and at the same time, the mechanical strength of the molded article is lowered, which is preferable Absent. Also, the particle size of the inorganic filler is 0.01 to 100 μm in average particle size.
m range, preferably 0.1 to 30 μm, more preferably 0.5
-10 μm is suitable. If it is less than 0.01 μm, agglomerates are likely to occur on the surface of the molded product due to poor dispersion, and if it exceeds 100 μm, the surface roughness of the surface after etching becomes large, and a good appearance cannot be obtained.

As a method of blending these inorganic fillers into the liquid crystalline polyester, various methods are used, but it is preferable to uniformly knead the mixture by a melt kneading method using an extruder prior to molding,
It is preferable to disperse.

The liquid crystalline polyester in the present invention is a melt-processable polyester and has a property that polymer molecular chains take a regular parallel arrangement in a molten state. The state in which the molecules are arranged in this manner is often called a liquid crystal state or a nematic phase of a liquid crystal substance. Such polymer molecules are generally elongated, flattened, fairly stiff along the long axis of the molecule, and have multiple chain extension bonds, usually in either coaxial or parallel relationship. Consists of.

The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using a crossed polarizer. More specifically, the anisotropic molten phase can be confirmed by using a Leitz polarization microscope and observing the molten sample placed on the Leitz hot stage under a nitrogen atmosphere at a magnification of 40 times. The polymer is optically anisotropic. That is, it transmits light when inspected between crossed polarizers. If the sample is optically anisotropic, polarized light will be transmitted even if it is stationary.

As the constituent component of the polymer forming the anisotropic molten phase as described above, one or more of aromatic dicarboxylic acid and alicyclic dicarboxylic acid is used. 1 of aromatic diol, alicyclic diol and aliphatic diol One or more Aromatic hydroxycarboxylic acids One or more Aromatic thiol carboxylic acids One or more Aromatic dithiols, aromatic thiol phenols 1
One or more, selected from aromatic hydroxyamine, one or more of aromatic diamine, etc., and the polymer forming the anisotropic molten phase consists only of polyester II) consisting of I) Polyester III) consisting of polyester IV) and polythiol ester consisting only of V) Polythiol ester consisting of V) VI) and polythiol ester VII) consisting of polyesteramide VIII) and a combination of polyesteramide consisting of Is a polyester that forms an anisotropic melt phase composed of

Furthermore, although not included in the category of the combination of the above components,
Aromatic polyazomethine is included in the polymer forming the anisotropic melt phase, and specific examples of such a polymer include poly (nitrilo-2-methyl-1,4-phenylene nitriloethylidyne-1,4-phenyleneethyl). Lysine); poly (nitrilo-2-methyl-1,4-phenylene nitrilomethylidine-1,4-phenylenemethylidine); and poly (nitrilo-2-chloro-1,4-phenylene nitrilomethylidine-1,4) -Phenylenemethylidine).

Furthermore, although not included in the category of the combination of the above components,
Polyester carbonate is included as a polymer forming the anisotropic molten phase. It consists essentially of 4-oxybenzoyl units, dioxyphenyl units, dioxycarbonyl units and terephthaloyl units.

Polyesters of I), II), III) and V which are polymers forming an anisotropic melt phase suitable for use in the present invention.
The polyesteramide of III) can be produced by various ester forming methods that allow organic monomer compounds having functional groups that form the required repeating units by condensation to react with each other. For example, the functional groups of these organic monomer compounds may be carboxylic acid groups, hydroxyl groups, ester groups, acyloxy groups, acid halides, amine groups and the like. The organic monomer compound can be reacted by a molten acidolysis method without the presence of a heat exchange fluid. In this method, the monomers are first heated together to form a molten solution of the reactants. As the reaction continues, solid polymer particles become suspended in the liquid.
Volatile by-products of the final stage of condensation (eg acetic acid or water)
A vacuum may be applied to facilitate removal of the.

Further, a slurry polymerization method can also be adopted to form a liquid crystalline polyester suitable for use in the present invention. In this way, the solid product is obtained in suspension in the heat exchange medium.

Liquid crystalline polymers suitable for use in the present invention tend to be substantially insoluble in common solvents and are therefore unsuitable for solution processing. However, as already mentioned, these polymers can be easily processed by conventional melt processing methods.

Liquid crystalline polyesters suitable for use in the present invention generally have a weight average molecular weight of about 2,000 to 200,000, preferably about 10,0.
It is from 00 to 50,000, particularly preferably from about 20,000 to 25,000.
On the other hand, suitable wholly aromatic polyesteramides generally have a molecular weight of about 5,000 to 50,000, preferably about 10,000 to 30,00.
It is 0, for example, 15,000 to 17,000. The measurement of such molecular weight is a standard measurement method without gel permeation chromatography and other polymer solution formation,
For example, it can be carried out by quantifying the end groups of the compression molded film by infrared spectroscopy. The molecular weight can also be measured by using a pentafluorophenol solution and using a light scattering method.

The polymer exhibiting the anisotropic melt phase used in the present invention is preferably an aromatic polyester and an aromatic polyesteramide, and a polyester partially containing the aromatic polyester and the aromatic polyesteramide in the same molecular chain is also a preferable example. .

Preferred examples of compounds constituting them are 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene and 1,4
-Naphthalene compounds such as dihydroxynaphthalene and 6-hydroxy-2-naphthoic acid, biphenyl compounds such as 4,4'-diphenyldicarboxylic acid and 4,4'-dihydroxybiphenyl, the following general formulas (I), (II) or ( III)
Compound represented by: (However, X: alkylene (C _{1 to} C ₄ ), alkylidene, -O
A group selected from —, —SO—, —SO ₂ —, —S—, and —CO— Y :—( CH ₂ ) _n — (n = 1 to 4), —O (CH ₂ ) _n O— (n
= 1 to 4)) p-hydroxybenzoic acid, terephthalic acid, hydroquinone, para-substituted benzene compounds such as p-aminophenol and p-phenylenediamine, and their nucleus-substituted benzene compounds (substituents are chlorine). , Bromine, methyl, phenyl, 1-phenylethyl), isophthalic acid, resorcin, and other meta-substituted benzene compounds.

The liquid crystalline polyester used in the present invention may be a polyalkylene terephthalate which does not partially show an anisotropic melt phase in the same molecular chain, in addition to the above-mentioned constituents. In this case, the alkyl group has 2 to 4 carbon atoms.

Among the above-mentioned constituents, a compound containing one or more kinds of compounds selected from naphthalene compounds, biphenyl compounds and para-substituted benzene compounds as essential constituents is a further preferable example. Of the p-position-substituted benzene compounds, p-hydroxybenzoic acid, methylhydroquinone and 1-phenylethylhydroquinone are particularly preferable examples.

Particularly preferred anisotropic melt phase forming polyesters for use in the present invention include repeating units containing naphthalene moieties such as 6-hydroxy-2-naphthoyl, 2,6-dihydroxynaphthalene and 2,6-dicarboxynaphthalene. It is contained in an amount of about 10 mol% or more. Preferred polyesteramides are those containing repeating units of the above-mentioned naphthalene moieties and moieties consisting of 4-aminophenol or 1,4-phenylenediamine.

Incidentally, specific examples of the compounds constituting the above-mentioned I) to VIII) and specific examples of the polyester forming the anisotropic molten phase which is preferable for use in the present invention are described in JP-A-61-6986.
It is described in Japanese Patent No. 6 publication.

In the present invention, in addition to the above-mentioned specific inorganic filler, other various kinds of combined inorganic substances can be blended for the purpose of improving various characteristics. Such a combined inorganic material is preferably blended in order to obtain a molded article excellent in properties such as mechanical properties, heat resistance, and dimensional stability (deformation resistance, warpage). A granular or plate-like combined inorganic material is used.

As the fibrous filler, glass fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum Inorganic fibrous substances such as fibrous substances of metals such as titanium, copper, and brass.

On the other hand, as the powdery inorganic material, carbon black, graphite, glass beads, milled glass fiber, glass balloon, glass powder, iron oxide, oxides of metals such as alumina, other ferrite, silicon carbide, silicon nitride, boron nitride, etc. Can be mentioned.

Examples of the plate-like inorganic material include mica, glass flakes, various metal foils and the like.

These combined inorganic materials can be used alone or in combination of two or more.

Particularly preferably used combined inorganic substances are fibrous inorganic substances, especially glass fibers, and the amount thereof is in the range of 1 to 60% by weight, preferably 5 to 50% by weight based on the total weight of the molded article composition.
40% by weight. However, it is not preferable that the total content of the inorganic filler and the combined inorganic material exceeds 85% by weight in the composition of the molded product from the viewpoint of moldability and various physical properties. or,
A single filling of only fibrous inorganic material has a slightly high surface roughness and is not suitable for plating for decoration purposes. The fibrous inorganic material used in combination has a diameter of 1 to 30 μm,
If the length is in the range of 5 μm to 1 mm, preferably 10 μm to 100 μm, especially when glass fiber is combined with the above-mentioned inorganic filler, unexpectedly the surface of the molded product becomes more uniform, and the molded product becomes conductive by plating. When forming a circuit,
It was found that the adhesion was improved. From the viewpoint of the balance between the surface roughness and the mechanical properties of the material, milled fiber glass, which is between the glass fiber and the fine powder glass, is particularly preferable.

If necessary, it is desirable to use a sizing agent or a surface treatment agent when using these inorganic fillers and combined inorganic materials.

The composition of the present invention has no adverse effect even if a conventionally used nucleating agent is used in combination therewith.

Further, the composition of the present invention may be supplemented with other thermoplastic resin to the extent that the intended purpose thereof is not impaired within the scope of the present invention.

The thermoplastic resin used in this case is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polyacetal (homo or copolymer), polystyrene, polyvinyl chloride, polyacrylic acid ester, and copolymers thereof. , Polyamide, polycarbonate, ABS, polyphenylene oxide, polyphenylene sulfide, fluororesin and the like. Further, two or more kinds of these thermoplastic resins can be mixed and used.

Further, known substances added to general thermoplastic resins and thermosetting resins, that is, stabilizers such as plasticizers, antioxidants and ultraviolet absorbers, antistatic agents, surface treatment agents, flame retardants, dyes and pigments. Colorants such as the above, lubricants for improving fluidity and releasability, lubricants, crystallization accelerators (nucleating agents) and the like can be appropriately used according to the desired performance required.

〔The invention's effect〕

As described above, according to the pretreatment method for plating a liquid crystalline polyester resin molded article of the present invention, it is possible to uniformly roughen the surface of the resin molded article, and to impart the catalyst, which is essential in the process, extremely uniformly. As a result, the plating property is improved, and it has become possible to develop applications for printed wiring boards, which have been so far expected but could not be put to practical use.

〔Example〕

Hereinafter, the treatment method of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Examples 1 to 8 Liquid crystalline polyester resin A described later and the fillers shown in Table 1 (% by weight represents a value relative to the total amount of the composition) were kneaded and dispersed by an extruder to form pellets, After drying at 140 ℃ for 3 hours, 140 ~ 160 by molding machine
A 50 mm × 70 mm × 3 mm flat plate was molded using a mold whose temperature was adjusted to ℃.

The shaped flat plate was plated according to the steps described below. The etching conditions were the conditions shown in the table.

After etching, after neutralizing the remaining liquid after attachment, use the amphoteric surfactant shown in Table-1 to immerse it in a 1 wt% solution to fully activate the roughened surface and evenly attach the catalyst in the next step. Made easy.

After performing electroless copper plating at 25 ℃ for 20 minutes, 60 at 150 ℃
After drying for a minute, the plate was allowed to stand at room temperature for 1 day, and the state of plating adhesion was observed to determine the effect of the amphoteric surfactant. The judgment was expressed by the number of the 10 flat plates tested that could be confirmed to adhere to the entire surface.

Good electroless plating is electroplated continuously, and it is observed that there is no dissolution or blistering during plating, and after plating, it is dried at 150 ° C for 60 minutes and then left at room temperature for 1 day for adhesion. Was observed to determine the electroplating property. Similar to the above judgment, the judgment was expressed by the number of flat plates without blister.

Comparative Examples 1 to 5 A flat plate prepared in the same manner as in Example 1 was used and subjected to a surfactant treatment after the plating treatment under the conditions shown in Table 1. However, a good plating state such as when an amphoteric surfactant was used was obtained. I couldn't get it.

Examples 9 to 13 Similar evaluations were made except that the liquid crystalline polyester A used in Example 1 was replaced with other liquid crystalline polyesters B to F.

The results are shown in Table-1.

No difference was observed for any of the base polymers under the same conditions.

The liquid crystalline polyester used in the examples has the following structural units.

Claims (4)

[Claims] 1. A liquid crystalline polyester characterized in that a molded article made of a melt-processible polyester capable of forming an anisotropic melt phase is surface-roughened with an alkaline aqueous solution and then treated with an amphoteric surfactant aqueous solution. Pretreatment method for plating resin molded products. 2. A melt-processable polyester capable of forming an anisotropic melt phase is a group II element of the periodic table and its oxides, sulfates, phosphates, silicates, or aluminum, silicon, tin, lead, A liquid crystalline polyester resin composition containing 5 to 80% by weight of the total amount of the molded article composition, and one or more inorganic fillers selected from the group consisting of antimony and bismuth elements and oxides thereof. A method for pre-plating a liquid crystalline polyester molded article according to claim 1, which is a product. 3. The pretreatment method for plating a liquid crystalline polyester resin molded article according to claim 1, wherein the alkaline aqueous solution is an aqueous solution containing 20% by weight or more of a hydroxide of an alkali metal or an alkaline earth metal. 4. An amphoteric surfactant is a carboxybetaine type,
The pretreatment method for plating a liquid crystalline polyester molded article according to any one of claims 1 to 3, which is an amphoteric surfactant selected from a sulfobetaine type, an aminocarboxylic acid salt type, and an imidazoline derivative type.