JPS63150348A - Polyamide composition having excellent platability - Google Patents

Abstract

PURPOSE:To provide the title compsn. having excellent plate adhesion, heat resistance, mechanical strengths, rigidity and appearance, by blending polytetramethyleneadipamide having a specified relative viscosity with wollastonite powder and other inorg. powder. CONSTITUTION:35-90wt.% polytetramethyleneadipamide (A) having a relative viscosity of 1.5-6, pref. 2.5-5.0 (a soln. obtd. by dissolving 1g of the polymer in 100ml of sulfuric acid at 30 deg.C) (e.g., nylon 46) is blended with 5-65wt.% wollastonite (B) which is mainly composed of calcium metasilicate, contains not more than 4wt.% impurities and has a particle size of not larger than 10mu, pref. 0.2-5mu, 0-40wt.% inorg. filler (C) other than the component B (e.g., calcium titanate) and optionally, a polymer (e.g., PB), an antioxidant, a stabi lizer, a lubricant, etc. (D). The mixture is melt-kneaded at 300-340 deg.C to obtain the title compsn. The compsn. is molded. The surface of the molded product is roughened by etching and plated.

Description

Detailed Description of the Invention a. Industrial Application Field The present invention relates to a polyamide composition, and more specifically, a polyamide composition for metal plating that has excellent heat resistance, mechanical strength, rigidity, appearance, and especially plating adhesion. Regarding.

b. Prior Art Conventionally, resin plated products have been mainly manufactured by etching ABS resin with a mixture of chromic acid and sulfuric acid and then plating, and have been widely used in automobiles, electrical/electronic, and miscellaneous goods parts. However, since ABS resin does not have very high heat resistance, mechanical strength, rigidity, etc., its use is mainly limited to decorative purposes.

In addition, in recent years, in order to reduce the weight of automobiles due to rising energy costs, there is a trend to use resin even for metal-plated parts that require heat resistance, mechanical strength, rigidity, etc.

Polyamide resin has excellent heat resistance, mechanical strength, rigidity, etc., but conventional polyamide resin plated products have good appearance but have insufficient adhesion strength, and products with high adhesion strength have insufficient appearance. Currently, the scope of its use is limited.

Therefore, it has excellent heat resistance, mechanical strength, rigidity, etc., and is made of ABS.
There is a demand for polyamide resins with excellent plating properties that combine resin appearance with stable plating adhesion strength.

Problems to be Solved by the C0 Invention As a result of intensive studies on polyamide resin for plating with improved plating properties, the present inventors have developed a method of adding wollastonite of a specific particle size to nylon 46 having a specific relative viscosity. It was discovered that by blending the polyamide resin composition, the appearance and adhesion strength of the metal plated part were improved, and it was possible to obtain a polyamide resin composition with excellent surface contact, mechanical strength, and rigidity, and in completing the present invention. It has arrived.

d. Means for Solving the Problems The present invention provides: (a) polytetramethylene adipamide having a relative viscosity of 1.5 to 6 and 35 to 90% by weight) powdered wollastonite having an average particle size of 10 μm or less;
The present invention provides a polyamide resin composition having excellent plating properties, characterized in that it contains 5 to 55% by weight of carbon dioxide and 0 to 40% by weight of an inorganic filler other than (C) and (b).

Nylon 46 used in the present invention is a polyamide consisting essentially of repeating structural units represented by the following formula.

壬NH-(CHz)<-NH-CO-(CHz)4-C
D) For its manufacturing method, see, for example, JP-A-56-1.
No. 49430, No. 56-149431, No. 58-83
Examples include methods described in Japanese Patent Publication No. 029 and Japanese Patent Publication No. 60-28843.

The relative viscosity (η-t: measured with a solution of 1 g of polymer dissolved in 100 ml of 97% sulfuric acid at 30° C.) of nylon 46 is 1.5 to 6, preferably 2.5 to 5.0.

If the relative viscosity of nylon 46 is less than 1.5, even if wollastonite or other inorganic fillers are added, the mechanical properties of the resulting molded product will deteriorate, and the plating adhesion strength will decrease. This is not desirable because it does not provide a level of quality.

On the other hand, if the relative viscosity of nylon 46 exceeds 6, not only will the moldability decrease, but also the dispersibility of wollastonite and other inorganic fillers will decrease, resulting in greater variation in plating adhesion strength. A problem also arises in the appearance of the plating.

The content of nylon 46 in the polyamide composition of the present invention is 35 to 90% by weight, preferably 45 to 70% by weight. If it is less than 35% by weight, the moldability and molded appearance of the resulting polyamide composition will be significantly reduced. On the other hand, 90
If it exceeds % by weight, the adhesion strength of the metal plating of the resulting polyamide composition will be insufficient, which is not preferable.

The wollastonite used in the present invention is mainly composed of calcium metasilicate (CaSiOx),
Depending on where it is produced, aluminum oxide (A1) may be an impurity.
20. ), iron oxide (FeO-Fe, O,), calcium carbonate (CaCOz), calcium hydroxide (Ca(O,)
fl) z ), magnesium oxide (MgO), manganese dioxide (MnOz), etc., and their contents are different, so when used to improve the plating properties of nylon 46, carbonate in impurities If the content of calcium and calcium hydroxide is high, it will adversely affect the appearance of the molded product, especially the adhesion. Therefore, the content of impurities such as calcium carbonate and calcium hydroxide contained as impurities in wollastonite should preferably be reduced. It is 4% by weight or less, more preferably 2.5% by weight or less.

The calcium carbonate and calcium hydroxide contents in wollastonite are
This can be determined by the weight loss rate after heating (burning loss), and if it exceeds 4% by weight, uneven etching may occur.
Further, in the chemical plating process, calcium carbonate in wollastonite reacts with acid to generate a large amount of carbon dioxide gas, which is undesirable because the appearance and adhesion strength of the plating surface are significantly reduced.

Further, in the present invention, the average particle size of the wollastonite is preferably 10μ or less, more preferably 0.2 to 5μ.
μ, and within this range, particularly excellent plating surface appearance and plating adhesion strength can be obtained. If the average particle size exceeds 10 μm, the surface of the resin molded product will be excessively roughened by etching, making it impossible to obtain a beautiful mesh appearance comparable to that of ABS resin. On the other hand, if the average particle size is 0.2 μm or less, the holes in the recesses formed on the surface of the molded product due to etching are too small, so that the anchoring effect for improving plating adhesion strength becomes undesirable.

The content of wollastonite in the polyamide composition of the present invention is 5 to 65% by weight, preferably 15 to 60% by weight, more preferably 25 to 45% by weight. If the content is less than 5% by weight, the heat resistance, mechanical strength, rigidity, etc. of the polyamide composition will be insufficient, and the plating adhesion strength will not be sufficiently improved. If the content exceeds 65% by weight, the molded product becomes brittle and the appearance of the plated surface deteriorates, which is not preferable.

In addition, in the present invention, other inorganic fillers (as C1, those used as ordinary resin reinforcing materials such as potassium titanate, clay, talc, silica, alumina, etc.) may be blended into the polyamide resin composition as necessary. be able to.

These can be used alone or in combination of two or more. Particularly preferred is potassium titanate. The blending ratio of the above inorganic filler is 1 to 40% by weight, preferably 5% by weight.
-35% by weight, more preferably 7-25% by weight. If it exceeds 40% by weight, it is not preferable because the moldability and impact resistance of the polyamide composition deteriorate and the adhesion strength of plating cannot be brought to the desired level. 1
If it is less than % by weight, the appearance of the plating will deteriorate.

The polyamide resin composition of the present invention may contain the following polymer components, if necessary.

For example, polybutadiene, butadiene-styrene copolymer, acrylic rubber, ethylene-propylene copolymer, EP
DM, styrene-butadiene block copolymer, polypropylene, butadiene-acrylonitrile copolymer, polycarbonate, PET, PBT, polyacecool, polyvinylidene fluoride, ethylene-vinyl acetate copolymer, polyisoprene, PPO resin, styrene-maleic anhydride These include acid copolymers.

Other anti-aging agents, stabilizers, lubricants, etc. can be added as necessary.

The method for preparing the polyamide composition of the present invention is not particularly limited, but for example, nylon 46, wollastonite, and potassium titanate are mixed in a Henschel mixer or a tumbler.
The mixture can be melt-mixed using a 40 mmφ vented twin-screw extruder at a cylinder temperature of 300 to 340°C.

As a method for molding the polyamide composition of the present invention, l
Each test piece can be molded using an oz injection molding machine. At this time, the molding temperature is 300~350°
C1 molding pressure is 30-50 kg/crA (G)
, mold temperature is 80°C 1 screw 1 rotation speed 15 Orp
It is m.

As a method for plating a molded article made of the polyamide composition of the present invention, the following pretreatment process, electroless plating process using a nickel sulfate solution, and electroplating process using a copper sulfate solution and a chromic anhydride solution are performed. is possible,
This can be done using a normal nylon resin plating process.

Furthermore, as a pretreatment for the above-mentioned plating treatment, it is necessary to roughen the surface of the molded article by notching it with hydrochloric acid or the like. The degree of surface roughening is 3 to 6μ.
It is desirable that For example, in the case of nylon 46/wollastonite/potassium titanate = 50/40/10 system plating, the thickness is about 5 μm.

e. Examples Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples. In addition, in Examples and Comparative Examples, all percentages indicate weight percent unless otherwise specified. In addition, molding conditions, molded product shape, plating recipe, performance evaluation method of plated products (surface gloss;
Adhesion strength) was determined according to the following method.

・Molding conditions Molding machine: Toshiba Machine (KK) Model 1580A injection molding machine Cylinder temperature: 300-350"c Injection pressure: 30-5Q kg/c+d (G)
Mold temperature 280℃ Molding cycle 712sec/20sec (injection/cooling)
・Molded product shape (3-stage plate with texture) Length 120mm, width 40mm, thickness 1.6-3.2m
・Plating recipe/adhesion strength Make a strip of 1 cm width on the film surface of the test piece for measuring plating adhesion strength, and measure the peel strength (kg/cm) of the plating film at an angle of 90°C and a peeling rate of 30++n/min. did.

・Measurement points for adhesion strength Adhesion strength often varies depending on the measurement location.

If there is a large difference in the measurement values depending on the measurement location, the variation in adhesion strength will be large.In particular, the measurement value near the gate may be extremely low. 2.4 m).

- Judgment of surface gloss Using a test piece for plating surface gloss judgment, surface gloss was judged according to the following criteria.

◎: Reflects light like a mirror and has a surface gloss equivalent to ABS resin plating.

○: Slightly worse than ABS resin plating, but has some practical uses.

62 The surface is cloudy and reflects light diffusely.

×: The surface is satin-like and has no specularity at all.

・Thermal cycle test A thermal cycle test was conducted under the following conditions using a test piece for determining plated surface gloss, and the environmental temperature resistance of the plated molded product was evaluated.

[-40℃; 3 hours] Moan [Room temperature: 30 minutes] Moan [165
℃=3 hours〕Mourning〔165℃: 3 hours〕Mourning〔Room temperature=30
The process of ] is counted as one cycle, and this process is repeated 5 times.

Examples 1 to 4 After premixing the following nylon 46, wollastonite, and potassium titanate in the proportions shown in Table 1, the mixture was heated in a cylinder at 300 to 340°C using a 45-tsuru φ pent-type twin-screw extruder. Molding pellets were prepared by melt mixing at one temperature. This pellet was molded under the molding conditions described above. The obtained molded product was metal plated using the above plating recipe, and its adhesion strength, surface gloss, and environmental temperature resistance through thermal cycling were evaluated. The results are shown in Table 1.

In addition, molded products before plating treatment (hereinafter referred to as unplated products)
Regarding the mechanical properties of the ASTM
Evaluation was made using a test piece, and the results are also listed in Table-1.

Table 1 shows that a plated molded article having the characteristics targeted by the present invention was obtained from the resin composition of Example 1.2.3.4.

Comparative Examples 1 to 3 Nylon 46, wollastonite, and potassium titanate similar to those in Example 1 were premixed in the proportions shown in Table 1, and then 300 to 34
Molding pellets were prepared by melt mixing at a cylinder temperature of 0°C. This pellet was molded under the above molding conditions, and the resulting molded product was metal plated using the plating recipe described above, and its plating adhesion strength, plating surface gloss, and environmental temperature resistance through thermal cycling were evaluated. The results are shown in Table 1. Indicated. The mechanical properties of the molded products before plating were evaluated using ASTM test pieces molded using conventional methods, and are also listed in Table 1.

As a result, the composition of Comparative Example 1.2 was prepared with a wollastonite content of less than 5% by weight and more than 55% by weight, which is outside the range of the present invention, but was similar to that of Example. As a result of evaluation using the method described above, the plating adhesion strength and environmental temperature resistance in thermal cycle tests were poor, and the desired plating properties could not be obtained.

In addition, the composition of the comparative example is a case where the content of potassium titanate is adjusted to 42% by weight, which exceeds the range of the present invention,
As a result of evaluation in the same manner as in the examples, the plating appearance, environmental temperature resistance due to thermal cycling, impact strength, etc. were poor, and the desired physical properties were not obtained.

Comparative Examples 4-5 The composition of Comparative Example 4 contained Example 3 in place of Nylon 46.
A resin composition was prepared using nylon 66 with a composition ratio similar to that of 66, and its physical properties were evaluated, but the plating appearance, plating adhesion strength, environmental temperature resistance due to thermal cycling, etc. were inferior, and it was not suitable for the purpose. Physical properties could not be obtained.

The composition of Comparative Example 5 was obtained by preparing a resin composition using nylon 66 in the same composition ratio as in Example 4 instead of nylon 46, and evaluating its physical properties. It had poor environmental temperature resistance due to thermal cycling, and the desired plating properties could not be obtained.

10 Effects of the Invention The polyamide composition of the present invention improves plating adhesion strength, which was a drawback of conventional metal plating resins, by blending wollastonite having a specific average particle size with nylon 46 in a specific ratio. It is possible to obtain a resin composition that significantly improves plating properties such as the surface appearance of plating and deterioration due to thermal cycling, and has an excellent balance of physical properties such as mechanical properties and impact resistance.

Furthermore, it is possible to mold a molded product with less variation in plating properties. Therefore, the metal-plated molded product made of the polyamide composition of the present invention has an excellent balance of physical properties, so it can be used for molding of automobile exterior parts, interior parts, various parts in the electrical and electronic fields, etc., which require a high level of quality. The industrial use value is extremely large for providing products.

Claims (2)

[Claims] (1) (a) Polytetramethylene adipamide with a relative viscosity of 1.5-6 35-90% by weight (b) Powdered wollastonite with an average particle size of 10μ or less
A polyamide resin composition having excellent plating properties, characterized in that it contains 5 to 65% by weight of fillers (c) and 0 to 40% by weight of inorganic fillers other than (b). (2) A polyamide composition with excellent plating properties as set forth in claim (1), wherein the inorganic filler (c) is potassium titanate and its content is 1 to 40% by weight. thing.