JPH0819251B2 - Surface treatment method for liquid crystalline polyester resin moldings - Google Patents

Description

The present invention relates to a surface treatment method for a melt-processable polyester (hereinafter simply referred to as "liquid crystalline polyester") resin molded article capable of forming an anisotropic molten phase.

More specifically, a surface treatment for efficiently obtaining a liquid crystalline polyester resin molded product having excellent heat resistance and excellent moldability having surface characteristics suitable for surface decoration by printing, painting, vapor deposition, plating, etc. and bonding with an adhesive. About the law.

[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.

Although injection molding processing methods that are generally performed can be applied to such liquid crystalline polyesters, the surface of the molded product tends to peel off and fluff due to the strong orientation of the surface of the molded product. Secondary processing by is not possible. Therefore, it is conceivable to perform a surface roughening treatment using a chemical such as that used for a conventional general resin. However, the surface is chemically extremely inactive and there is no suitable solvent having affinity, and the surface layer is not chemically reactive. The orientation layer cannot be removed to roughen the surface.

On the other hand, thermally, liquid crystalline polyester has a low coefficient of linear expansion comparable to that of general metals, and has a heat resistance that does not cause abnormalities even when immersed in a solder bath at 260 ° C for 10 seconds. However, there is a need for a surface treatment method that improves the above-mentioned surface characteristics for the purpose of using the above characteristics for the purpose of applying to a component and a substrate to which a metal is bonded by an adhesive and a substrate to which plating is applied, but it is still satisfactory. There is no known cure.

[Means for solving problems]

The present inventors take advantage of such thermally beneficial characteristics of the liquid crystalline polyester, chemically activate the surface without impairing the physical and chemical properties, and do not generate a surface layer that easily peels off. As a result of diligent research on the method, a molded article made of a composition in which a liquid crystalline polyester contains a specific inorganic filler in an amount of 5 to 80% by weight (relative to the total amount of the composition) is used. By adopting the combination condition of specific material composition and specific etching solution, such as contact treatment with an aqueous solution containing alkaline earth metal hydroxide as the main component, the surface processability of liquid crystalline polyester resin molded products is significantly improved. Find out what to do,
The present invention has been completed.

The inorganic filler used in the present invention is one or more selected from the group consisting of oxides, sulfates, phosphates and silicates of elements of Group IIa or IIb of the periodic table.

Oxides of elements of Group II of the periodic table are compounds such as magnesium oxide, calcium oxide, barium oxide and zinc oxide, and phosphates are magnesium phosphate, calcium phosphate, barium phosphate, zinc phosphate, Compounds such as magnesium pyrophosphate, calcium pyrophosphate, etc., sulfates are compounds such as magnesium sulfate, calcium sulfate, barium sulfate, etc., and silicates are compounds such as magnesium silicate, calcium silicate, talc, wollastonite, etc. is there.

These inorganic fillers are preferably used in the surface treatment method particularly when plating is performed as the secondary processing, and phosphate is particularly preferable.

The blending amount of these inorganic fillers is 5 to 80% by weight, preferably 20 to 70% by weight based on the total amount of the liquid crystalline polyester resin composition.
% By weight. If it is less than 5% by weight, a non-uniform flow mark will be generated on the surface of the molded product, and if the surface layer of the molded product is pasted with an adhesive tape and peeled off, a thin skin-like peeling easily occurs. Occurs. 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. Further, the inorganic filler is preferably in the form of fine powder, and the particle diameter thereof is suitably in the range of 0.01 to 100 μm, preferably 0.1 to 30 μm, and more preferably 0.5 to 10 μm. 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.

The aqueous solution containing an alkali metal hydroxide or an alkaline earth metal hydroxide as a main component in the etching treatment liquid of the present invention is sodium hydroxide, potassium hydroxide,
An aqueous solution of an alkali metal hydroxide such as lithium hydroxide,
It is an aqueous solution of a hydroxide of an alkaline earth metal such as strontium hydroxide or barium hydroxide, preferably an aqueous potassium hydroxide solution. This aqueous solution further dissolves the surface decomposition product of the liquid crystalline polyester and is soluble in an alkaline aqueous solution, for example, an organic solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl alcohol, a furan compound such as tetrahydrofuran, 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 dipping treatment conditions in the etching solution are searched for optimal conditions depending on the composition of the etching solution.
Although selected, general treatment conditions are the above-mentioned hydroxide 20-60.
40% to 50% by weight of hydroxide, preferably 40% to 50% by weight of aqueous solution at 30 to 80 ° C. for 3 to 120 minutes.
It is 10 to 30 minutes at 60 ° C. 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 in the present invention is a melt-processable polyester and has a property in which polymer molecular chains take a regular parallel arrangement in a molten state. The state in which molecules are arranged in this manner is often referred to as a liquid crystal state or a nematic phase of a liquid crystal substance. Such polymer molecules are generally elongated, flat, and fairly stiff along the long axis of the molecule,
Consisting of polymers having a plurality of chain extension bonds, usually in either a coaxial or parallel relationship.

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 components of the polymer forming the anisotropic molten phase as described above, one composed of one or more of aromatic dicarboxylic acid and alicyclic dicarboxylic acid One of aromatic diol, alicyclic diol and aliphatic diol One or more aromatic hydroxy carboxylic acids one or more aromatic thiol carboxylic acids one or more aromatic dithiols, aromatic thiol phenols
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

Further, although not included in the category of the combination of the above components, the polymer forming the anisotropic molten phase includes aromatic polyazomethine, and specific examples of such a polymer include:
Poly (nitrilo-2-methyl-1,4-phenylene nitriloethylidyne-1,4-phenyleneethylidine); poly (nitrilo-2-methyl-1,4-phenylene nitrilomethylidyne-1,4-phenylenemethylidine ); And poly (nitrilo-2-chloro-1,4-phenylene nitrilomethylidine-1,4-phenylenemethylidine).

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

The polyesters of the above I), II) and III) and the polyesteramides of VIII), which are polymers forming an anisotropic molten phase suitable for use in the present invention, have a functional group capable of forming a required repeating unit by condensation. It can be produced by various ester forming methods capable of reacting the organic monomer compounds with each other. For example, the functional groups of these organic monomer compounds are carboxylic acid groups, hydroxyl groups, ester groups, acyloxy groups, acid halides,
An amine group may be used. The above-mentioned organic monomer compound can be reacted without a heat exchange fluid by a melt acidosis method. 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. Vacuum may be applied to facilitate removal of volatiles (eg acetic acid or water) by-produced in the final stage of the condensation.

Also, a slurry polymerization method can be employed for forming a liquid crystalline polyester suitable for use in the present invention. in this way,
The solid product is obtained in suspension in a heat exchange medium.

Liquid crystalline polymers suitable for use in the present invention tend to be substantially insoluble in common solvents and therefore unsuitable for solution processing. But 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 1
It is preferably from 20,000 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,
000, for example, 15,000 to 17,000. The measurement of such a molecular weight can be carried out by a standard measurement method which does not involve solution formation of gel permeation chromatography and other polymers, for example, by quantifying an end group by infrared spectroscopy on a compression molded film. 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
Aromatic polyesters and aromatic polyesteramides are preferable, and aromatic polyesters and polyesters partially containing aromatic polyesteramides in the same molecular chain are also preferable examples.

Preferred examples of compounds constituting them are 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene,
1,4-dihydroxynaphthalene and 6-hydroxy-2
-Naphthalene compounds such as naphthoic acid, biphenyl compounds such as 4,4'-diphenyldicarboxylic acid and 4,4'-dihydroxybiphenyl, the following general formulas (I), (II) or (II)
Compound represented by I): (However, X: alkylene (C _{1 to} C ₄ ), alkylidene, -O
A group selected from —, —SO—, —SO ₂ —, —S—, and —CO— Y :—( CH ₂ ) _h — (n = 1 to 4), —O (CH ₂ ) _h 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.

Further, 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 components, those containing one or more compounds selected from a naphthalene compound, a biphenyl compound and a para-substituted benzene compound as essential components are more preferable examples. Of the p-position-substituted benzene compounds, p-hydroxybenzoic acid, methylhydroquinone and 1-phenylethylhydroquinone are particularly preferable examples.

Particularly preferred polyesters that form an anisotropic melt phase for use in the present invention include repeating units containing a naphthalene moiety such as 6-hydroxy-2-naphthoyl, 2,6-dihydroxynaphthalene and 2,6-dicarboxynaphthalene. About 10
It is contained in an amount of not less than mol%. Preferred polyesteramides are those containing repeating units of the naphthalene moiety described above and a moiety consisting of 4-aminophenol or 1,4-phenylenediamine.

Specific examples of the compounds constituting the above-mentioned I) to VIII) and polyesters forming an anisotropic melt phase which are preferable for use in the present invention are described in JP-A-61-69.
It is described in Japanese Patent No. 866.

In the present invention, in order to improve various properties, in addition to the above-mentioned specific inorganic filler, other various inorganic substances in combination can be further blended. 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 (modification resistance, warpage). A granular or plate-like combined inorganic material is used.

As the fibrous inorganic material, glass fiber, carbon fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, plasticized silicon 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, silica, quartz powder, glass beads, milled glass fiber, glass balloon, glass powder, iron oxide, antimony trioxide, oxides of metals such as alumina, other ferrites, carbonization Examples thereof include silicon, silicon nitride, boron nitride and the like.

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

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

Particularly preferably used combined inorganic substances are fibrous 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 material has a slightly high surface roughness and is not suitable for plating for decoration purposes.
As a substance to be used in combination, a diameter of 1 to 30 μm and a length of 5 μm
Unexpectedly, the surface of the molded product is further homogenized to form a conductive circuit on the molded product, which is unexpectedly when 1 mm, preferably in the range of 10 μm to 10 μm, particularly glass fiber is combined with the inorganic filler. It has been found that the adhesion of the plating is improved. Milled fiber glass, which is located between glass fiber and fine powder glass, is particularly preferable in terms of balance between surface roughness and mechanical properties of the material.

When using these inorganic fillers and combined inorganic substances, it is desirable to use a sizing agent or a surface treatment agent if necessary.

The composition of the present invention does not adversely affect the use of a conventionally used nucleating agent.

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. These thermoplastic resins can be used as a mixture of two or more kinds.

Further known substances added to general thermoplastic resins and thermosetting resins, namely, plasticizers, stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, surface treatment agents, surfactants,
Flame retardants, colorants such as dyes and pigments, lubricants for improving fluidity and releasability, lubricants, crystallization accelerators (nucleating agents), etc. may be appropriately used according to the desired performance required. it can.

In the present invention, it is also possible to treat the molded article by a known method before, after or simultaneously with etching. For example, heat treatment, hot water treatment, or immersion treatment in a solution containing a specific compound before or after etching is performed. Such post-etching treatment includes neutralization of the etching solution,
It can also be combined with steps such as washing and drying.

〔The invention's effect〕

As described above, according to the surface treatment method for a liquid crystalline polyester resin molded article of the present invention, the surface layer of the resin is not easily peeled off, has a uniform and dense surface structure, and is bonded to a paint or an adhesive. Highly adhesive, further strengthens the adhesion of the plating, does not cause high-temperature peeling due to the difference in thermal expansion coefficient with the metal, which was difficult with thermoplastic resins up to now, and solder dipping (processing time about 10 seconds) It has become possible to develop not only for exterior parts but also for printed wiring boards.

〔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 and Comparative Examples 1 to 4 Liquid crystalline polyester resin A described later and the fillers shown in Table 1 were kneaded and dispersed by a melt kneading method using an extruder, pelletized, and dried at 140 ° C. for 3 hours. After that, a test piece was molded using a mold whose temperature was controlled at 150 to 160 ° C. by a molding machine, and the molded flat plate was tested for various surface characteristics in the following manner. The results are shown in Table 1.

(1) Releasability of surface layer resulting from orientation of surface Cellophane tape (Nichiban Co., Ltd.)
Made, 18mm width) and press it with your finger (about 500g),
The tape was peeled off at an angle of 90 ° and the peeling property of the surface layer was visually evaluated.

Evaluation ◎ ... No surface layer peeling at all ○ ... Surface layer peeling almost nothing △… Partial surface layer peeling ×… Almost adheres to the tape surface and causes surface layer peeling (2) Flow mark or uneven flow of molded product The surface was visually evaluated.

Evaluation ◎… Uniform surface ○… Almost uniform surface △… Partially flow marks ×… Flow marks all over the surface (3) Variation in surface roughness due to etching treatment Alkaline degreasing liquid (Okuno Pharmaceutical Co., Ltd.) Aceline A220) at 60 ° C for 5 minutes, thoroughly degreased and washed with water, then in a 45% by weight potassium hydroxide aqueous solution at 60 ° C.
Etching was carried out for 30 minutes. The etched molded product is washed with water and then immersed in a 5% by weight solution of hydrochloric acid at room temperature for 3 minutes to neutralize the alkali content adhering to the surface, rinse with water, and then dry in a hot air circulation oven at 80 ° C for 15 minutes. did. The maximum roughness was measured at three points on the etched surface with a surface roughness meter (surfcorder SE3C manufactured by Kosaka Laboratory) for the purpose of investigating the roughness of the surface of the molded product after the pretreatment for etching.

(4) Adhesiveness of the surface-treated molded product After the molded ASTM tensile test piece was etched in the same manner as in (3), an epoxy adhesive (Cemedine EP-00) was used.
7, 2 liquid type) is applied to each tip part (overlap length 1 cm) divided into two parts at the center of the dumbbell test piece, and laminated.
After standing at room temperature for 24 hours, the tensile load was measured with a universal testing machine, and the shear strength per 1 cm ² was determined and shown as the tensile shear strength.

(5) Plating adhesion strength of surface-treated molded product After plating an etched flat plate (50 x 70 x 3 mm) according to the following procedure, insert a 1 cm wide band-shaped cut with a cutter knife to make the tip at a 90 ° angle. The force of peeling up and gripping the tip with only the spring and peeling it off is the adhesion strength of the plating (kg / c
m).

Examples 9 to 13 Flat plates were molded in the same manner as in Example 2 except that the liquid crystalline polyesters B to F were used instead of the liquid crystalline polyester A, and the same evaluation was performed, and the results shown in Table 2 were obtained.

Examples 14 to 19 For the materials used in Example 4, flat plates of 50 × 70 × 3 mm were molded and the surface treatment properties were evaluated using various etching solutions. The results shown in Table 3 were obtained.

Example 20 The plated part of the plated product obtained in Example 9 was cut into a strip having a width of 10 mm and immersed in a solder bath at 260 ° C. for 10 seconds.
When the adhesion of the plating was evaluated, the adhesion was 1.5 kg / cm and there was almost no decrease in adhesion.

Examples 21 to 23, Comparative Examples 5 to 7 Liquid crystalline polyester resin A and the fillers shown in Table 4 were pelletized in the same manner as in Example 1 to form test pieces. The peelability of the surface layer of the molded test piece was measured in the same manner as in Example 1, and the other tests were measured in the following manner. The results are shown in Table-4.

(6) Material Strength The tensile strength of the molded test piece was measured by ASTM D638.

(7) Paintability of the surface-treated molded product After the molded product was etched in the same manner as in (3), a commercially available urethane paint (Retan PG6 manufactured by Kansai Paint Co., Ltd.)
0) to a dry film thickness of 30 ± 10 μm and apply at 100 ℃
After being dried for 60 minutes at room temperature, it was allowed to stand at room temperature for 1 day, and the adhesion strength of the coating film was evaluated by a method of peeling a cellophane tape with a mess. The size of the goggles is 1 mm square × 100 pieces, and the evaluation result is expressed by the number of remaining goggles / total number of goggles.

Comparative Examples 8 and 9 Polybutylene terephthalate (PBT) was used as an ordinary thermoplastic polyester that does not exhibit liquid crystallinity in Example 2.
Using "Duranex" manufactured by Polyplastics Co., Ltd., equivalent prescription materials were evaluated in the same manner. Also,
As Comparative Example 9, PBT containing no filler was also compared and evaluated. The results are shown in Table-5.

In the case of PBT, there is no strong orientation on the surface when it is not filled, and it is easily subjected to surface etching with potassium hydroxide, and orientation occurs conversely due to the filler containing glass fiber, and the etched surface is roughened faster than liquid crystalline polyester. The surface became rough, and no equipment or plating with good appearance could be obtained.

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

Claims (3)

[Claims] 1. A melt-processable polyester capable of forming an anisotropic melt phase, which is selected from the group consisting of oxides, sulfates, phosphates and silicates of elements of Group IIa or IIb of the Periodic Table, or Two to more than two types of inorganic fillers, based on the total weight of the composition 5 to 80
A liquid crystallinity characterized by subjecting a molded article composed of a liquid crystalline polyester resin composition which is contained by weight% to a contact treatment with an aqueous solution containing a hydroxide of an alkali metal or a hydroxide of an alkaline earth metal as a main component. Surface treatment method for polyester resin molded products. 2. The surface treatment method for a liquid crystalline polyester resin molded article according to claim 1, wherein the inorganic filler is in the form of fine powder having an average particle size of 0.01 to 100 μm. 3. The molded product further comprises, in addition to the above inorganic filler, a fibrous inorganic material having a diameter of 1 to 30 μm and a length of 5 μm to 1 mm, based on the total weight of the molded product composition. The surface treatment method for a liquid crystalline polyester resin molded article according to claim 1 or 2, which comprises a composition blended in a weight percentage.