JPH0440426B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for metallizing the surface of a polybutylene terephthalate resin molded article by plating. More specifically, the present invention relates to a method for producing a surface-metallized polybutylene terephthalate resin molded product that has excellent plating film adhesion and a good surface appearance. Generally, plastic plating treatment involves (1) pretreatment;
(2) Surface roughening treatment (etching), (3) Sensitizing treatment (4) Activation treatment (5) Electroless plating and (6) Electroplating processes The process from step (3) above is usually called the plating process. Among these, the surface roughening treatment (2) above is an important step that affects the adhesion of the metal plating film applied in the subsequent plating step, and various means are used depending on the type of plastic. As a means for roughening the surface of thermoplastic polyester resin in plating, for example, a method of roughening a polyester resin containing a filler in advance (Japanese Unexamined Patent Publication No. 15977/1982) is known.
Even if these were applied to polybutylene terephthalate resin with excellent crystallization properties, it was not possible to simultaneously satisfy both excellent plating film adhesion and good metal shine, making it a practical surface-metallized polybutylene terephthalate resin. It was not possible to obtain a molded product. The plating adhesion mechanism created by adding a filler to the polyester resin is that when the surface layer of a molded product is eroded by etching, there is a difference in the degree of erosion caused by the etching between the filler and the polymer part, resulting in unevenness on the surface. It is said that the surface is roughened, the plating metal precipitates there, and adhesive force is developed between the molded product and the plating film metal due to the anchor effect. For this reason, the deciding factor is what kind of unevenness is created on the surface by etching, and the shape, size, cohesiveness, etc. of the filler contained are important factors. In addition, the surface roughness after etching is an important factor for metallic luster, and at the same time, the surface roughness of the molded product itself before etching has a significant influence.
For this reason, in polymers with good crystallinity such as polybutylene terephthalate resin, depending on the type of filler, the contained filler may act as a crystal nucleating agent, leading to crystallization of polybutylene terephthalate and reducing surface roughness. This resulted in a loss of brightness and a decrease in commercial value. For example, in Example 2 of JP-A-54-15977,
A method of alkali treatment and plating treatment using a composition in which titanium oxide (KA30, manufactured by Titan Kogyo Co., Ltd.) is added to polybutylene terephthalate is described, but the KA30 manufactured by Titan Kogyo Co., Ltd. used here is a resin. Average particle size 0.5μ used as a white pigment for
The following titanium dioxide was used, and the effect of improving plating performance was insufficient. Therefore, the present inventors conducted intensive studies with the aim of obtaining a surface-metallized polybutylene terephthalate resin molded product that has excellent metal film glitter and plating adhesion at the same time. , size, cohesiveness, etc., and it was not easy to find a range of significant effects. However, the present inventors surprisingly found that the use of titanium oxide having a limited particle size range of 1 to 6 μm in average particle size produces significantly superior effects. Moreover, even if this average particle diameter of 1 to 6 μm is applied to other fillers such as calcium carbonate, gypsum, mica, clay, silica, calcium silicate, talc, calcium metasilicate, etc., there is no favorable plating performance improvement. No effect appears. That is, the average particle size of 1 to 6 μm is the optimum particle size unique to titanium dioxide, and the effect of improving plating performance is remarkable. However, the present inventors roughened the surface of a molded product made of a blend of polybutylene terephthalate and titanium dioxide having a specific average particle size using an alkaline solution, and then subjected it to a conventional plating process to obtain polybutylene terephthalate. It is possible to obtain a surface metallized polybutylene terephthalate resin that retains the properties of the resin itself, has excellent plating film adhesion, and at the same time has good surface brightness.
That is, for polybutylene terephthalate,
It has been found that when titanium dioxide having an average particle size in a very limited range of 1 to 6 μm is contained, a remarkable effect of specifically improving plating performance can be obtained. That is, the present invention provides a polybutylene terephthalate resin molded product containing 10 to 250 parts by weight of titanium dioxide with an average particle size of 1 to 6 μm to 100 parts by weight of polybutylene terephthalate, after roughening the surface using an alkaline solution. The present invention provides a method for producing a surface metallized polybutylene terephthalate resin, which is characterized by plating treatment. The polybutylene terephthalate used in the present invention is a polymer obtained by polycondensing a dicarboxylic acid component of which 90 mol% or more is a terephthalic acid component and a diol component whose main component is 1,4-butanediol. The terephthalic acid component mentioned here is terephthalic acid and its ester-forming derivatives, and other dicarboxylic acid components used together with the terephthalic acid component include isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,
5-naphthalene dicarboxylic acid, bis(P-carboxyphenyl)methane, anthracene dicarboxylic acid, 4,4'-diphenyl dicarboxylic acid, 1,2-
Aliphatic dicarboxylic acids such as bis(phenoxy)ethane-4,4'-dicarboxylic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,
Examples include alicyclic dicarboxylic acids such as 3-cyclohexanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, and ester-forming derivatives thereof. In addition, the diol component that can be used with 1,4-butanediol has 2 to 20 carbon atoms.
aliphatic glycols, such as ethylene glycol, propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, cyclohexanediol, etc., or long chains with a molecular weight of 400 to 6000. Glycols, namely polyethylene glycol, poly-
Examples include 1,3-propylene glycol, polytetramethylene glycol, and ester-forming derivatives thereof. Specific examples of these polymers and copolymers include preferably polybutylene terephthalate, polybutylene terephthalate isophthalate, polybutylene terephthalate decanedicarboxylate, polybutylene hexamethylene terephthalate, and the like. In addition, these polybutylene terephthalate resins have a relative viscosity of 1.2 to 2.0, especially 1.3 to 2.0, when a 0.5% O-chlorophenol solution is measured at 25°C.
A value in the range of 1.85 is preferred. Moreover, these can be used in combination of two or more types. The titanium dioxide used in the present invention is anatase-type and rutile-type titanium dioxide with a purity of 95% or more produced by a sulfuric acid method or a chlorine method. The average particle size of titanium dioxide must be in the range of 1 to 6 μm, and preferably 2 to 4.5 μm. Outside this range, for example, titanium dioxide (average particle size of 0.5 μm or less), which is often used as a white pigment for resins, is not very effective in improving plating performance, and only those with the above average particle size have a specific effect. It is. The average particle diameter here refers to the maximum frequency diameter (mode diameter) determined from the particle size distribution measured by the sedimentation balance method.
It is indicated by . If the average particle size is less than 1 μm, the effect of improving the adhesion of the plating film is small. If the thickness is 6 μm or more, the effect of improving the adhesion of the plating film is small, and the brightness of the plating is significantly inhibited, resulting in a decrease in commercial value. It goes without saying that the particle size distribution of titanium dioxide is preferably as sharp as possible. This is because, as described above, portions with small particle diameters and portions with large particle diameters have a small contribution to improving adhesive strength. However, it is extremely rare for titanium dioxide, which is normally produced industrially, to have an extremely wide particle size distribution. Sufficient adhesive strength can be obtained within this range. The amount of titanium dioxide added is 10 to 250 parts by weight per 100 parts by weight of polybutylene terephthalate, especially
30 to 100 parts by weight is preferred. If the amount is less than 10 parts by weight, the effect of improving the adhesion of the plating film is insufficient. If the amount exceeds 250 parts by weight, the surface roughness of the molded product becomes large, the adhesion of the plating film and the brightness of the plating are lost, and the mechanical properties of the thermoplastic polyester resin itself deteriorate, which is not preferable. In addition, polybutylene terephthalate and average particle size 1
When mixing ~6 μm titanium dioxide, other additives such as lubricants such as aluminum stearate and barium stearate, crystal nucleating agents such as talc, clay kaolin, and alumina, and mold release agents such as montan wax and montan acid wax metal salts are used. agent, plasticizer,
Heat stabilizers, ultraviolet absorbers, pigments, dyes, fibrous reinforcing agents, etc. can also be added as necessary. Polybutylene terephthalate, average particle size 1~
The means for blending the 6 μm titanium dioxide and other additives is arbitrary, and for example, a method of simultaneous mixing using a screw extruder or the like can be adopted. For the production of polybutylene terephthalate resin molded products from the compound, any ordinary thermoplastic resin molding methods such as injection molding, extrusion molding, and blow molding can be used. can be obtained easily. When plating according to the method of the present invention, it is important to first perform preliminary treatment such as wiping off the oil film on the surface of the molded article as necessary, and then roughen the surface using an alkaline solution. The alkaline solution used for surface roughening treatment is an alkali component such as potassium hydroxide, sodium hydroxide, magnesium hydroxide, etc., added to a solvent such as water, phenols, alcohols, etc., or a mixed solvent thereof to a concentration of 5 to 50%. Among them, aqueous solutions of sodium hydroxide and potassium hydroxide are preferably used. The conditions for this surface roughening treatment (alkali etching) are preferably that the molded product is immersed in an alkaline solution at 30 to 95°C for 1 to 120 minutes, and then thoroughly washed. After the alkali etching treatment is completed, the molded article may be sufficiently washed with water, and then further surface treated with an acidic aqueous solution having a PHH3 or less. In this case, the acid component used is a mineral acid such as sulfuric acid or hydrochloric acid, and the appropriate treatment conditions are 5 to 70°C for 2 to 600 seconds. By subjecting the polybutylene terephthalate resin molded product that has been surface-roughened in this way to a conventional plating treatment, a surface-metallized polybutylene terephthalate resin molded product with outstanding plating film adhesion and good surface brightness can be obtained. Obtainable. The plating process includes, for example, sensitizing with a stannous chloride solution - activating with a palladium chloride solution - electroless copper or nickel plating - each step of electroplating, or catalyststaining - accelerating - electroless plating - each step of electroplating. A conventional chemical plating method can be applied. By blending titanium dioxide having a specific average particle size according to the present invention and roughening the surface with an alkaline solution, the metal plating film has strong adhesion during the subsequent plating process and at the same time has excellent surface brightness. Although the mechanism by which this is obtained has not yet been fully elucidated, it is presumed to be as follows. That is, the titanium dioxide blended into polybutylene terephthalate and having an average particle size of 1 to 6 μm is dispersed in the polymer as agglomerated particles having irregularities. When polybutylene terephthalate is etched by alkali treatment, the agglomerates dissolve and fall apart, creating holes on the surface of the polybutylene terephthalate molded product with a size suitable for plating and an uneven shape inside, where the plating metal precipitates. It is thought that a plated product with excellent plated film adhesion and brightness can be obtained at the same time. To obtain holes with an effective anchor effect in this plating, the average particle size of titanium dioxide is 1 to 1.
The one with a diameter of 6μm is specifically effective.
Titanium dioxide (average particle size 0.5 μm or less), which is often used as a white pigment outside this average particle size range, and other fillers such as calcium carbonate, gypsum, mica, clay, etc. Silica, calcium silicate, talc, calcium metasilicate, etc. are not suitable for powder form and cannot improve plating performance. The reason why the plating performance improvement effect is small in the case of titanium dioxide with an average particle size of 1 μm or less is that although secondary agglomeration tends to occur in polybutylene terephthalate, the size of the agglomerated particles is small, and the flow shearing stage during molding It is thought that this is because the aggregated particles tend to collapse under the influence of water, making it difficult to reach the required size. Conversely, when the average particle size of titanium dioxide is 6 μm or more, secondary aggregation becomes difficult to occur, and even if large pores are obtained after etching, the inside of the pores will be uneven as in the present invention. It is considered that the desired effect of improving plating performance cannot be obtained because the shape does not have a shape having . Therefore, in the present invention, selection of the primary particle size (average particle size) of titanium dioxide is extremely important in order to obtain appropriate agglomerated particles. Furthermore, the reason why the same effects as the present invention cannot be obtained when using fillers other than titanium dioxide with an average particle size in the range of 1 to 6 μm is due to the difference in surface smoothness of these fillers. , because the aggregation properties in polybutylene terephthalate are completely different, and as a result, even if the primary particle size is the same, the secondary aggregation state in the molded product is completely different from that of titanium dioxide used in the present invention. It is thought that. The surface metallized polybutylene terephthalate resin molded article of the present invention has excellent heat resistance, mechanical properties, plating film adhesion, and surface brightness, and is therefore useful as various automobile parts, electrical parts, and mechanical parts. The effects of the present invention will be further explained below with reference to Examples. Examples 1 to 6, Comparative Examples 1 to 10 Titanium dioxide and others of various particle sizes shown in Table 1 are applied to 100 parts by weight of polybutylene terephthalate with a relative viscosity of 1.57 measured from a 0.5% orthochlorophenol solution at 25°C. The fillers were dry-blended in the proportions shown in Table 1, melt-kneaded using a screw extruder set at 250°C, and pelletized. Next, the obtained pellets were placed in an injection molding machine set at 250°C, and molded into 80mm x 80mm x 3 pellets at a mold temperature of 80°C.
mm each plate specimen was molded. Next, the test piece was placed in a 30% sodium hydroxide aqueous solution.
Immerse at 70℃ for 10 minutes, then soak in 2% hydrochloric acid aqueous solution for 30 minutes.
℃ for 10 seconds and then thoroughly washed under running water.
A test piece with a roughened surface was obtained. This roughened test piece was subjected to plating treatment by the method shown below. (1) Sensitizing...Sensitizing the test piece with stannous chloride
30 g, immersed in a solution consisting of 60 c.c. of hydrochloric acid (38%) and 1000 c.c. of water at 25°C for 2-5 minutes. (2) Washing with water. (3) Activating...The test piece was immersed in a solution consisting of 0.1 g of palladium chloride, 10 c.c. of hydrochloric acid (38%), and 1000 c.c. of water at 25°C for 1 to 3 minutes. (4) Washing with water. (5) Electroless copper plating...The test piece was prepared with 10 g of copper sulfate (pentahydrate), 40 c.c. of formalin (37%), 10 g of sodium hydroxide, 20 g of Rothsiel's salt, and 1000 g of water.
Chemical copper plating solution (PH10.0-11.5) consisting of cc
Soak for 10 minutes at 25-30℃. (6) Washing with water. (7) Electroplating (bright copper plating)...The test piece was prepared using 50 g of concentrated sulfuric acid, 200 g of copper sulfate (pentahydrate), and SCB-MU10c.c. and SCB-1 1c.c. (Okuno Pharmaceutical Co., Ltd.) as brighteners. Co., Ltd. product) and water in an acidic copper plating bath consisting of 1000 c.c. at a temperature of 25 to 30°C and a current density of
Electroplated for 60 minutes under 4A/ ^dm2 condition,
Forms a copper plating film approximately 60μ thick. (8) Washing with water. (9) Electroplating (bright nickel plating)... After bright copper plating, the test piece was coated with 40 g of boric acid, nickel chloride,
50g of hexahydrate, 300g of nickel sulfate heptahydrate,
Monolight 1c.c. and Acuna B-1 as brighteners
(produced by Okuno Pharmaceutical Co., Ltd.) and 1000 c.c. of water, and electroplated for 7 minutes at a temperature of 50°C and a current density of 5A/ ^dm2 to form a 7μ thick plate. Forms a nickel-metsuki film. (10) Wash with water. (11) Electroplating (chrome plating)...After bright nickel plating, the test piece was treated with 5g of sulfuric acid and 250g of chromium oxide.
The sample was placed in a chrome plating bath consisting of 1,000 c.c. of water and 1,000 c.c. of water, and plated for 1 minute at a temperature of 50°C and a current density of 40 A/dm ² to form a chrome plating film with a thickness of 0.25 μm. The plating film adhesion test was as follows: (7) A 1 cm wide cut was made on the test piece that had been electroplated (bright copper plating), and the adhesive surface was T-peeled in a 90° direction at a speed of 20 mm/min. This was done by measuring force (g). The plating brightness test was carried out by measuring the glossiness of the test piece that had been subjected to (11) electroplating (chrome plating). These results are shown in Table 1.

[Table] As is clear from the results in Table 1, the surface metallized polybutylene terephthalate resin molded product of the present invention provides excellent plating film adhesion and excellent plating brightness.

Claims (1)

[Claims] 1 A thermoplastic polyester resin molded product containing 10 to 250 parts by weight of titanium dioxide with an average particle size of 1 to 6 μm per 100 parts by weight of polybutylene terephthalate is roughened using an alkaline solution, and then plated. A method for producing a surface metallized polybutylene terephthalate resin molded product.