JPS60155239A - Polyamide resin molding - Google Patents

Abstract

PURPOSE:To improve the calcium chloride resistance, etc., of a molding comprising polyamide 6 and/or polyamide 66, and thereby prevent it from being crazed, by coating it with a thin film of a resin selected from among polyamides 610, 612, 116, 11, and 12. CONSTITUTION:A molding comprising polyamide 6 or/and polyamide 66 is coated with a thin polyamide resin film of a thickness of 10-750mu, selected from among polyamides 610, 612, 116, 11, and 12 to obtain the purpose polyamide resin molding. The method for forming the coating, for example, comprises preforming a film comprising a higher polyamide resin, attaching this film to a mold, placing polyamide 6 or 66 in the mold and molding it to form a film on the surface of the fromed molding. In this way, it is possible to improve the resistance to a calcium chloride-based antifreezer of a molding of a resin comprising polyamide 6 or 66 without detriment to its properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyamide resin molded product coated with a thin film made of a specific polyamide resin.

Polyamide 6 or polyamide 66 resin has been widely used as automobile parts in recent years due to its heat resistance, oil resistance, high strength and heat resistance.
As hood parts, for example, functional parts such as cooling fans, radiator tank tops and bases, cylinder head covers, oil pans, gears, valves, and other exhaust gas system parts and fuel system parts, or as external parts. bumper.

Applications to oil caps, etc. are attracting attention.

However, since polyamide 6 and polyamide 66 resins inherently have a strong affinity for inorganic metal salts, molded products made from these materials are susceptible to attack by metal salts such as calcium chloride and zinc chloride. It has the serious drawback that cracks occur within a short period of time. Especially in the winter, when antifreeze agents mainly composed of calcium chloride, which are sprayed in large quantities on roads to prevent roads from freezing, adhere to underhood parts that are exposed to high temperatures while driving, they can cause cracks in the parts. This can lead to car breakdowns and even personal injury.

Therefore, a method has been adopted in which the #lJ amide molded product is painted to form a coating film to improve its metal chloride resistance, but this method tends to produce many pinholes in the coating film, which causes adhesion. It has the disadvantage that metal chlorides penetrate through the pinholes and eventually cause cracks.

Therefore, the present inventors have developed a method that (1) does not impair the excellent heat resistance, high strength, and high rigidity of polyamide 6 and polyamide 66 resins, (2) has excellent chemical resistance, and (3) is inexpensive to mold. As a result of intensive studies aimed at obtaining a molded product made of polyamide 6 and/or polyamide 66 resin, a thickness of 10 to 750μ selected from at least one of polyamide 6101, polyamide 612, polyamide 116, polyamide 11, and polyamide 12 was found. It has been found that a polyamide molded article can be obtained by coating the polyamide resin with a thin film of polyamide 5 resin.

Hereinafter, the method for producing a molded product of the present invention and the effects of the molded product obtained by the method will be described.

The polyamide 6 or/and polyamide 66 resin referred to in the present invention refers to polyamide 6 or polyamide 6
6, a copolymer of polyamide 6 and polyamide 66, or a blend thereof.

In this sense we use the word and symbol 'or/and'. Furthermore, a small amount of other polyamide components may be copolymerized or blended within a range that does not significantly impair the physical properties of polyamide 6 and polyamide 66.

Next, a polyamide molded article is obtained. The molded article can be obtained by a known method, ie, injection molding, extrusion molding, or blow molding. During molding, preferably 10 to 60% by weight of glass fibers, carbon fibers, and other inorganic fillers such as wollastenite, talc, clay, glass beads, and organic fibers are mixed into the polyamide resin.

On the other hand, a polyamide resin for coating the polyamide molded product is prepared. Examples of this resin include polyamide 6101, polyamide 612, polyamide 116, polyamide 11.
selected from at least one type of polyamide 12 (hereinafter referred to as high-grade polyamide resin), preferably polyamide 61
2. selected from polyamide 111 or polyamide 12.

The polyamide resin molded product of the present invention can be produced by (a) preparing a film made of high-grade polyamide resin in advance, pasting the film on a mold, and then using polyamide 6 or/
and (b) fixing a pre-molded polyamide molded product in a mold and injection molding a high-grade polyamide resin onto the surface of the molded product. (C) A method of forming a film on a polyamide resin molded article by heat pressing, or (d) A thin film made of a high-grade polyamide resin with the same shape as the desired molded product. A molded product with
A method in which polyamide resin is molded after it is prepared in advance and fixed in a mold, or (e) polyamide 6 or/and polyamide 66 is molded from each cylinder using an injection molding machine having two cylinders. There is a method of forming a film by simultaneous injection molding of resin and high-grade polyamide resin, so-called two-color molding.
Particularly preferred methods are method (a), method (b), and method (e).

The thickness of the coating is lO~750μ, preferably 20~450μ
Let it be μ. If the thickness is less than lθμ, the method of forming a thin film is that if a pre-prepared film is used, the film may be torn by the molding pressure during molding, or if it is an injection molding method, it will not flow due to injection molding, so polyamide molding is not possible. A film cannot be formed on the entire surface of the product.

If the thickness exceeds 750μ, the ratio of the coating increases relative to the weight of the polyamide resin molded product covered, resulting in high costs and lowering the excellent heat resistance and rigidity of the molded product. Undesirable.

Since the polyamide resin molded product thus obtained has an extremely thin coating formed on its surface, the metal chloride resistance is significantly improved without impairing the properties of the molded product made of polyamide 6 and polyamide 66 resins. No cracks at all. Furthermore, since the weight of the thin film required to cover the molded product is small, it has the advantage of being inexpensive. Furthermore, unlike the paint film, there are no pinholes at all.

Examples of the present invention will be described in detail below.

The calcium chloride resistance of the molded products obtained in Examples and Comparative Examples was evaluated as follows.

After pre-humidifying the molded product in 100°C hot water for 4 Q hrs, 5% CaC1! The liquid was dropped onto the surface of the 5cc molded product and left in a gear oven at 100°C for 2 hrs.

After repeating this treatment (humidity adjustment→CaCl, dropwise addition→leaving in oven) in 1O cycles, the presence or absence of cracks on the surface of the molded product was confirmed using an optical microscope at a magnification of 30 times.

Example 1? A 20μ thick film made of Liamide 12 was prepared, and the film was attached to an injection molding machine 8 Machine 5J-35B (manufactured by 8 Machine Seisakusho) to form a small automotive wheel cap molded product (diameter 1001, wall thickness 3H). It was attached to the fixed side of the mold for the product. With the film attached, adjust the temperature of the mold to 80℃, close the mold, and then apply cylinder temperature 280℃ and injection pressure 450#/d1 molding cycle injection 1.
Polyamide 66 resin (0M3001G-30) reinforced with 30% glass fiber was molded under the conditions of 0 sec/cooling 12 SeC.

A molded product with no film tearing, uniform appearance, and good film adhesion was obtained.

The calcium chloride resistance of the molded product thus obtained was examined by the method described above, and it was found to be extremely excellent, with no cracks occurring even after 1O cycle treatment.

Comparative Example 1 Using the same mold as used in Example 1 and under the same molding conditions, a small wheel cap molded product (without coating) made only of 0M3001G-30 of Example 1 (diameter toom, wall thickness 3
ff dish-shaped molded product) was obtained.

As a result of evaluating the calcium chloride resistance of the molded product, it was only 1.
During the cycle treatment, cracks with a depth of about 0.2 fi were generated on the entire surface onto which the calcium chloride aqueous solution was dropped.

Example 2 A film with a thickness of 30μ made of polyamide 11 was prepared, and the film was used for a box-shaped molded product (width 50 mm x length 80 mm x height 20 mm) attached to an injection molding machine 8 machine 5J-35B.
Cod, wall thickness 2.5 fi) was pasted on the fixed side of the mold, and after the mold temperature was controlled (80°C) in the same manner as in Example 1, non-reinforced polyamide 6 was attached.
6 resin (CM3001 N) was injection molded under the conditions of a cylinder temperature of 280°C, an injection pressure of 400 #/d, and a molding cycle of 12 seconds of injection cooling and 5 seconds of cooling to obtain a box-shaped molded product covered with polyamide 11 film. Ta.

The obtained molded product had no film tearing, good film adhesion, and a uniform appearance.

The calcium chloride resistance of the thus obtained molded product was investigated by dropping an aqueous calcium chloride solution onto the surface covered with polyamide 1.1 film. As a result, the molded product did not develop any cracks even after 1O cycle treatment. It was a thing.

Comparative Example 2 Using the same mold as in Example 2 and under the same molding conditions, a box-shaped molded product was obtained using only 0M3001N without attaching a polyamide 11 film. As a result of examining the calcium chloride resistance of the box-shaped molded product, a large rack with a depth of 15 m was formed after only 1 cycle.

Example 3 A non-reinforced polyamide 6 resin (CMI 017
) A small wheel cap molded product was obtained by the same method as in Example 1, having a uniform appearance and good film adhesion and being coated with a polyamide 612 film.

The calcium chloride resistance was examined by dropping an aqueous calcium chloride solution onto the surface of the film, and the results showed that the molded product did not develop any cracks even after 10 cycles of treatment.

Comparative Example 3 A small wheel cap molded product was obtained by injection molding only CM1017 using the mold used in Example 3 and under the same molding conditions without pasting the polyamide 612 film.

As a result of investigating the calcium chloride resistance of the molded product, it was found that only 1 liter
During the cycle treatment, a large rack with a depth of about 1.6 nm was formed over the entire area where the calcium chloride aqueous solution was dropped.

Example 4 Using a 5J-35B injection molding machine, the cylinder temperature was 2.
80℃, mold temperature 90℃, injection pressure 350kg/d
, injection IQsec, cooling 10sec cycle, CIV
Injection molded from 13001 G-30, diameter 5ON.

Thickness 4. An Off disc molded product was obtained. The molded product has a diameter of 5
After fixing the mold in a cavity carved with a disc shape of 0.1 fi and 4.4 m thick, and controlling the temperature of the mold to 90°C,
Using a film gate with a thickness of 0.8 fi, a width of 15 fins, and a length of 2 fl, the cylinder temperature was 275°C, and the injection IQsec was
Polyamide 12 resin was injection molded under the conditions of one cooling cycle of 10 seconds.

Obtained letter molded product 1.10M3001G-30 thickness 4.
The surface of the OU° disc molded product was coated with polyamide 12 resin having a thickness of 420 μm.

The calcium chloride resistance of the molded product was examined by dropping an aqueous calcium chloride solution onto the surface coated with polyamide 12, and the result was that the molded product did not crack at all even when subjected to LO cycle treatment.

Example 5 Films made of polyamide 11 with thicknesses of 12μ, 20μ, and 28μ were prepared, and each film was attached to the fixed side of a mold for a small automobile wheel cap molded product in the same manner as in Example 1.

After that, in the same manner as in Example 1, after closing the mold, the glass m-fiber 30 was
96 reinforced polyamide 6@fat (CMlollG-30) was molded. As shown in Table 1, for wheel cap molded products coated with films having various thicknesses,
A molded product with no film tearing, uniform appearance, and good film adhesion was obtained.

As a result of examining the calcium chloride resistance of the thus obtained molded product, as shown in the table, it was found to be extremely excellent, with no cracks occurring even after 10 cycles of treatment.

Comparative Example 4 A polyamide 11 film with a thickness of 7 μm was prepared and an attempt was made to coat a CMI 011G-3°- wheel cap molded product with the polyamide 11 film in the same manner as in Example 5, but the film was not torn during molding. Therefore, it was not possible to obtain a molded product with a good appearance.

Claims (1)

[Claims] Polyamide molded products made of polyamide 6 or/and polyamide 66 are prepared by polyamide 610, polyamide 612, polyamide 116, polyamide 11. At least one type of polyamide 12) Selected thickness lO ~ 7
A polyamide resin molded product coated with a 50μ thin film of polyamide resin.