JPS6014775B2 - Surface treatment method for molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for surface treatment of a molded article, which provides a surface of the molded article suitable for plating, painting, printing, vacuum deposition, and the like.

Polypropylene has excellent mechanical properties and chemical resistance, so it is widely used for textiles, films, and large-scale injection molding. It could not be used for applications such as printing, vacuum deposition, etc.

Therefore, corona discharge treatment, flame treatment, electron beam treatment, saddle treatment, etc. are currently being performed for the purpose of surface damage of polypropylene molded products.

However, these processing methods have drawbacks such as limitations on the shape of the molded product, overly complex processing equipment, and extensive post-processing.

In order to improve these drawbacks, attempts have been made to copolymerize propylene with other monomers such as ethylene, but this method has the drawback that the above-mentioned physical properties inherent to polypropylene are impaired.

The inventors of this application completed this invention as a result of research into a method for surface treatment of molded articles obtained from polypropylene that does not have the above-mentioned drawbacks.

This invention improves the surface of a molded article obtained by molding a composition in which crystalline polypropylene is blended with a heat stabilizer and 0.02 to 5 parts by weight of magnesium benzoate per 10 parts by weight of crystalline polypropylene. The present invention relates to a method for surface treatment of molded articles, characterized by treatment with a boiling point aliphatic hydrocarbon solvent. The crystalline polypropylene used in this invention includes a crystalline homopolymer of propylene,
Block copolymers with propylene and other Q-olefins, such as ethylene and butene-1, whose content in the copolymer is about 15% by weight or less, or propylene and the content in the copolymer with about 5% by weight. Examples of the following other olefins include random copolymers with ethylene and butene-1, mixtures thereof, and mixtures thereof with up to about 5% by weight of ethylene-propylene copolymer rubber.

Among these, a crystalline propylene homopolymer, an ethylene-propylene block copolymer with an ethylene content of 15% by weight or less, and an ethylene-propylene sorandom copolymer with an ethylene content of 4.5% by weight or less are used. It is preferable that the flow index (abbreviated as MI) is 1.0 or more. Thermal stabilizers used in this invention include 2,6-di-tert-butyl-P-cresol, 2,
6-di-tert-butylphenol, 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-methylenebis(3-methyl-6-tert-butylphenol),
4,4'-bis(2,6-di-tert-butylphenol),
4,4'-thiobis(2-methyl-6-tert-butylphenol), 4,4'-thiopis(3-methyl-6-tert-butylphenol), 6-(4-hydroxy-3,5-
di-tert-butylaniline)-2,4-bis(n-octylthio)-1,3,5-triazine,tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane , octadecyl-3-(
3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 1,1.3,1-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 2,2
'-methylenebis(4-methyl-6-tert-butylphenol), 4,4-butylidenepis(3-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,
Examples include phenolic thread antioxidants such as 4,6 tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene. Furthermore, along with these phenolic antioxidants, didodecyl-3,3'-thiodipropionic acid ester, dioctadecyl-3,3'-thiodipropionic acid ester, and distearyl-3,3'-thiodiph. Dialkyl-3,3'-thiodipropionate esters such as lopionate esters, organic phosphorus compounds such as trilauryl phosphite, trilauryl thiophosphite, tris(nonylphenyl) phosphite, aliphatic carboxylic acids such as calcium stearate Antioxidants such as metal salts may be used in combination. The amount of heat stabilizer may be any amount that can prevent thermal deterioration of crystalline polypropylene during molding, etc., and is usually 0.0 parts by weight of crystalline polypropylene.
The amount is 5 to 0.5 parts by weight. In this invention, 0.02 to 5 parts by weight per 10 parts by weight of crystalline polypropylene,
Preferably, a composition containing 0.05 to 1.5 parts by weight of magnesium benzoate is used.

the amount of magnesium benzoate is less than the lower limit;
Even if the surface of the molded product is treated with a low-boiling aliphatic hydrocarbon solvent, it will not be possible to obtain a molded product surface suitable for plating, painting, etc., and if the amount of magnesium benzoate is greater than the above upper limit, the molded product will deteriorate. This is not preferred because physical properties such as tensile strength and elongation deteriorate.

A composition obtained by blending the heat stabilizer and magnesium benzoate with crystalline polypropylene by a blending method known per se is molded into various shapes by a molding method known per se, such as injection molding, extrusion molding, blow molding, and vacuum forming. Form into a product.

In the present invention, the surface of the molded article obtained as described above is treated with a low aliphatic hydrocarbon solvent.

Examples of the low-boiling aliphatic hydrocarbon solvent used in this invention include bentane, hexane, isohexane, heptane, isohebtan, and isooctane, which have a boiling point of 35 to 1.
Examples include 0pi0 aliphatic hydrocarbons.

Among these aliphatic hydrocarbons, bentane, hexane, and isohexane are preferably used. The treatment of the surface of the molded article with a low-boiling aliphatic hydrocarbon solvent is preferably performed at a temperature below the boiling point of the low-boiling aliphatic hydrocarbon solvent, particularly at about 30 to 100°C.
This can be carried out by bringing the molded article into contact with the low-boiling aliphatic hydrocarbon solvent, such as by immersing the molded article in the low-boiling aliphatic hydrocarbon solvent for 1 second to 10 minutes at a temperature of .

By using a low boiling point aliphatic hydrocarbon solvent in the present invention, the solvent remaining on the surface of the molded article after the surface treatment of the molded article can be removed in a short time.

According to the method of the present invention, a molded product having a surface suitable for plating, painting, printing, vacuum deposition, etc. can be obtained from a molded product of any shape, especially an injection molded product with a complicated shape, by a simple operation. be able to.

Next, examples and comparative examples will be shown.

Example 1 100 parts by weight of additive-free polypropylene (M,1,1), 0.1 part by weight of distearyl-3,3'-thiodipropionic acid ester, tetrakis-[methylene 3-(3,5-
Ditert-butyl-4-hydroxyphenyl)propionate] 0.05 parts by weight of methane, 0.05 parts by weight of lucium stearate
．． 0.5 parts by weight of magnesium benzoate and 0.1 parts by weight of magnesium benzoate were dry blended, and the resin temperature was adjusted to 230°C using an extruder.
I made a beret with 3 sides x 5 sides.

From this beret, a disc having a thickness of 2.16 mm and a diameter of 10 mm was molded using an injection molding machine under normal molding conditions. The disks were treated by immersing them in boiling n-hexane for 5 minutes and then dried at room temperature for 2 hours.

The disc treated with n-hexane was plated in the following manner.

Plating process (pre-treatment process) Chemical etching solution composition: Sulfuric acid 6% by volume, 1% by volume from phosphoric acid, 3% by volume by water, Potassium dichromate 15% by volume, Processing conditions: 1 powder at 65±5℃ Sensitizing treatment liquid composition: 10 cc of stannous chloride/15 cc of hydrochloric acid/15 cc of hydrochloric acid Processing conditions: 5 minutes at room temperature {3} Activating liquid phase composition: 0.2 cc of palladium chloride/10 cc of hydrochloric acid Chemical nickel treatment Nickel chloride aqueous solution, 20 minutes at room temperature (electroplating process) '5} Strike nickel plating 50 Soil, 2 minutes at 5℃ {61 Bright copper sulfate, 1 minute at room temperature [7} Chrome plating 55 Table 1 shows the results of observing the condition of the plating film after hand bending the chromium-plated test piece obtained at ℃ for 2 minutes.

In addition, for the test piece obtained by plating the photo-sulfuric acid steel in the photo-selective sulfuric acid steel plating process of the plating process (①) until the plating film thickness reached approximately 30 mm, the peeling width was 25 (
5.4) Table 1 shows the results of measuring the peeling strength (adhesion strength) of the plating film at a peeling rate of 25 legs/min. Example 2 The same procedure as in Example 1 was carried out except that the disk was treated by immersing it in boiling n-heptane for 5 seconds.

Table 1 shows the results of observing the state of the plating film after bending the chrome-plated test piece by hand, and the results of measuring the peel strength of the plating film of the photo-selective sulfuric acid steel plated test piece. Shown below.

Comparative Example 1 The same procedure as in Example 1 was carried out except that magnesium benzoate was not blended with additive-free polypropylene.

The results are shown in Table 1. Comparative Example 2 The same procedure as in Example 1 was carried out except that the disks were not treated with n-hebutane.

The results are shown in Table 1. Table 1 Example 3 Example 2 was carried out in the same manner as in Example 1 except that MI9 additive-free polypropylene was used instead of MII additive-free polypropylene.
．． A disk with a thickness of 16 ribs and a height of 10 ribs was molded.

The surface of this disk was treated with n-hexane in the same manner as in Example 1. This n-hexane treated disc was painted in the following manner.

Painting 1 Spray an olefin-based one-coat type paint (manufactured by Origin Denki) on the disc surface treated with n-hexane, set it for 10 minutes, and then force dry it at 60°C for 30 minutes to form a coating with a film thickness of approximately 10 mm. Formed the waist.

On the obtained painted disk, draw a cross mark with a cutter, cut a 100th grid on the 1st side of the pitch with a multi-cross cutter, and apply cellophane tape (product name: Elpack N manufactured by Nichiban).
o. 24) was brought into close contact with the disc and then rapidly peeled off at 460°C to conduct a peel test to examine the adhesion between the coating film and the disc. Adhesion is indicated by the number of squares on the grid that remain without peeling. Peel test 2
Table 2 shows the average values of the tests. Painting 2 Spray an olefin base coat (manufactured by Oil Top Coating) on the disc surface treated with n-hexane, and after setting for 1 minute, spray a urethane-based top coat (manufactured by Oil Top Paint),
After setting for 30 minutes, it was forced to dry at 8 and 0 for 30 minutes to form an undercoat film with a thickness of about 8R and a top coat with a film thickness of about 18R.

The obtained coated discs were subjected to a peel test in the same manner as described above, and the results are shown in Table 2.

Comparative Examples 3 to 4 Same as Example 3 except that magnesium benzoate was not blended with additive-free polypropylene (Comparative Example 3) or the disc was not treated with n-hexane (Comparative Example 4) carried out.

The results are shown in Table 2. Example 4 The same procedure as in Example 3 was carried out except that the disk was treated by immersing it in boiling n-hebutane for 5 seconds.

The coated disks obtained in the same manner as in Example 3 were subjected to a peel test in the same manner as described above, and the results are shown in Table 2.

Comparative Example 5 The same procedure as Example 4 was carried out except that magnesium benzoate was not blended with additive-free polypropylene.

The results are shown in Table 2. Examples 5-6 The same procedure as in Example 1 was carried out, except that instead of the additive-free polypropylene of MII, an ethylene-propylene block copolymer with an MI of 9 and an ethylene content of 7% by weight was used, with a wall thickness of 2.16,
A disc with a low sail of 0 was molded.

The surface of this disk was treated with n-hexane as in Example 1 (Example 5) or with n-heptane as in Example 2 (Example 6). These n-hexane-treated discs or n-heptane-treated discs were painted in the same manner as in Example 3. The obtained coated discs were subjected to a peel test in the same manner as described above, and the results are shown in Table 2.

Comparative Example 6 The same procedure as in Example 5 was carried out except that magnesium benzoate was not blended with the additive-free ethylene-propylene block copolymer.

The results are shown in Table 2. Examples 7 to 8 In the same manner as in Example 1, except that MI9, an ethylene-propylene random copolymer with an ethylene content of 2.5% by weight was used instead of the additive-free polypropylene of MII, a wall thickness of 2.16, and a thickness of 10 A disk for the portboard ◇ was molded.

The surface of this disk was treated with n-hexane as in Example 1 (Example 7) or with n-hebutane as in Example 2 (Example 8). These discs treated with n-hexane or discs treated with n-hexane were painted in the same manner as in Example 3 and subjected to a peel test. The results are shown in Table 2. Comparative Example 7 The same procedure as Example 7 was carried out except that magnesium benzoate was not blended with the additive-free ethylene-propylene random copolymer.

The results are shown in Table 2. Table 2

Claims (1)

[Claims] 1. The surface of a molded product obtained by molding a composition in which crystalline polypropylene is blended with a heat stabilizer and 0.02 to 5 parts by weight of magnesium benzoate per 100 parts by weight of crystalline polypropylene is coated with a low-boiling aliphatic A method for surface treatment of molded products, characterized by treatment with a hydrocarbon solvent.