JPH0128772B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface roughening polyacetal resin, and more specifically, the present invention relates to a method for surface roughening of polyacetal resin, and more specifically, pyridine having novel surface properties particularly suitable for surface decoration such as printing, painting, metal vapor deposition, bonding with adhesives, and surface coating such as metal plating. This invention relates to a surface roughening method for obtaining resin molded products. In general, plastics, especially polyacetal resins, are chemically stable and the surface of molded products made by injection molding etc. is smooth, so they have poor surface activity, and can be used for surface decoration by printing, painting, vapor deposition, adhesion with adhesives, metal plating, etc. surface coating is difficult to apply. Several attempts have been made to improve the surface coverage of these materials. For example, there is a method of treating the surface of the molded product with phosphoric acid, a method of treating it with chromium sulfuric acid, etc.
No. 19876, etc.). However, the surface properties of polyacetal resin molded products obtained by implementing these treatment methods also
It cannot be said that it is sufficiently suitable for the above-mentioned surface decoration and surface coating, and, for example, it has not been possible to provide a metal-plated product with a beautiful appearance and high plating peel strength. Subsequently, as an improved invention of the above-mentioned U.S. Patent No. 3,554,880, a method of immersing the molded product surface in an aqueous solution of pyridine, quinoline, γ-butyrolactone, etc. as a pre-process of treating the surface with phosphoric acid for the purpose of more uniform surface roughening. has been found (U.S. Patent No.
3905877, 3963590). However, when these substances are used industrially, there are problems in terms of odor and toxicity. In view of the above, the present inventors conducted intensive research to find an industrially easy-to-use and effective substance different from the above-mentioned substances, and found that it does not have the above-mentioned drawbacks, and at the same time, when immersed in a solution of the substance, polyacetal resin molding We have discovered a substance that can achieve a higher level of uniformity of plating adhesion on each part of a product, and have accomplished the present invention. That is, the present invention provides (a) polyacetal resin
100 parts by weight, (b) 0 to 35 parts by weight of carbonates, phosphates, acetates or mixtures thereof of metals of Group Group of the Periodic Table, and (c) unsaturated polyesters, alkyl esters of acrylic acid or methacrylic acid, Polymers, copolymers or mixtures thereof of compounds selected from the group of amides of acrylic acid or methacrylic acid, triallyl cyanurate, diallyl phthalate, vinyl acetate and divinylbenzene 0-20
When surface roughening a molded article obtained by molding a polyacetal resin composition consisting of parts by weight into a desired shape, 3-
Hydroxypyridine, 3-pyridinemethanol,
A compound selected from 2-pyridine methanol, 2-pyridine ethanol, 4-phenylpyridine, pyridine-4-aldehyde, 2-aminopyridine, nicotinic acid methyl ester, nicotinic acid ethyl ester, isonicotinic acid methyl ester, and isoquinoline. The present invention relates to a method for roughening the surface of a polyacetal resin molded article, which method comprises immersing it in a solution containing the polyacetal resin. In the present invention, it is more preferable for the polyacetal resin to contain various salts of group metals of the periodic table, and the purpose thereof is to more easily form a more complex roughened surface suitable for surface processing. In other words, when various salts of Group Group metals of the periodic table are dispersed and dotted in the polyacetal continuous phase, they are easily decomposed and removed by an appropriate acid, leaving traces as a roughened surface. Among the various salts of Group Group metals of the periodic table used in the present invention, examples of preferable carbonates include calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, and the like, with calcium carbonate being the most preferable. In addition, when the above-mentioned various salts are included, the content should be 2 to 35 parts by weight based on 100 parts by weight of the polyacetal resin, taking into consideration the balance between the effect of improving roughening properties and the decrease in mechanical properties and thermal stability. It is preferable that there be. In the present invention, the above (c) such as unsaturated polyester
This component is particularly effective when component (b) is present, and its purpose is to improve the thermal stability of the resin composition and to prevent cracking during surface roughening. The amount added is determined by taking into account the purpose and degree of effectiveness, and the balance with the mechanical strength of the resin, but it is preferably 0.01 to 20 parts by weight per 100 parts by weight of the polyacetal resin. The most distinctive feature of the method of the present invention is that before the polyacetal resin molded article is immersed in an acidic roughening solution, it is immersed in a solution of a specific compound. Improved plating adhesion and high degree of uniformity are achieved, but the specific compound is 3-
Hydroxypyridine, 3-pyridinemethanol,
Examples include 2-pyridine methanol, 2-pyridine ethanol, 4-phenylpyridine, pyridine-4-aldehyde, 2-aminopyridine, nicotinic acid methyl ester, nicotinic acid ethyl ester, isonicotinic acid methyl ester, and isoquinoline. Among these, 3-hydroxypyridine and 3-pyridinemethanol are particularly preferred since they are odorless. The reason why these compounds are effective may be found in their chemical structure, three-dimensional structure, etc., but so far, this has not been theoretically elucidated, and therefore, it is difficult to find compounds that are effective. It is difficult to predict from the structure. For example, 2-hydroxypyridine, nicotinic acid, isonicotinic acid, etc., which are generally considered to be very similar to the above compounds, do not have the effects aimed at by the present invention. The above object of the present invention can be achieved by immersing a polyacetal resin molded article in a solution containing these compounds and then in an acidic roughening solution, but the concentration of the compound in the solution used in this case is In consideration of the balance between the effect of improving plating adhesion strength and the appearance of the final product obtained, the content is preferably about 3 to 25% by weight. Further, from the same viewpoint, the immersion treatment conditions are more preferably 40 to 80°C for 3 seconds to 10 minutes. The polyacetal resin used in the present invention may be a homopolymer, that is, a polymer obtained by polymerizing formaldehyde or trioxane (including those whose terminals have been stabilized), or a polymer obtained by polymerizing formaldehyde or trioxane, or a polymer obtained by polymerizing trioxane and a cyclic ether, a cyclic It may be a binary, ternary or more copolymer obtained by copolymerizing comonomers such as acetal. The composition of the present invention includes various additives normally added to polyacetal resins, such as heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, crystal nucleating agents,
There is no problem even if pigments are added. In order to obtain the composition of the present invention, it is preferable to mix the constituent components using a device, such as a kneader, roll mill, or extruder, which is normally used for kneading resin melts. An extruder is most preferable from the viewpoint of blocking oxygen and working environment. The mixing temperature is above the melting point of the polyacetal resin used. This is determined by the need to uniformly mix the polyacetal resin in its molten state. The upper limit of the temperature is generally limited by the stability of the polyacetal resin used against thermal decomposition, and the mixing is usually carried out at a temperature below 250°C, preferably below 230°C. Component (c) of polymers such as unsaturated polyesters for improving thermal stability and preventing cracking may be mixed directly as a polymer, or may be added in the form of a monomer or prepolymer and then added in an extruder. They may be superimposed. In the case of thermosetting polymers, the latter is preferred. In addition, it is preferable to pre-mix each component using a tumbler or Henschel mixer in order to make a homogeneous composition, and it is preferable to use the polyacetal resin in a powdered state for stable supply to the extruder. Although preferred, these are not required. In addition, in the case of the method of adding the above-mentioned monomer or prepolymer, it is preferable to maintain a temperature at which a polymerization reaction does not occur during premixing. In the case of the above method of adding monomers or prepolymers, the heating conditions for polymerizing them are, for example, 190°C x 1 to 10 minutes, depending on the type of monomer or prepolymer. It is.
This condition can be achieved in most cases by the typical temperature and time combinations (determined by the extrusion speed) used when mixing polyacetal resin compositions using conventional extruders, or by other auxiliary heating means. However, the present invention does not impose any limitations on the heating method itself. Further, a polymerization initiator may be added to the composition. There are various ways to confirm that the polymerization of the added monomer or prepolymer is completed by the above heating and that no unreacted materials remain. There are methods for checking by odor, and further checking by immersing pellets in a solvent and checking whether unreacted substances are extracted using infrared spectrophotometry. The polyacetal resin composition of the present invention produced by the above method is usually made into a molded product using an injection molding machine (an extruder or other machine may be used depending on the shape of the molded product), and then pre-etched according to the present invention. It is then etched with a suitable acid. As a result, a polyacetal resin molded product having the desired excellent surface workability can be obtained. Suitable acids for use in etching the polyacetal resin composition of the present invention include any acidic or oxidizing liquid that can decompose the various salts of Group Group metals of the periodic table blended as described above. However, it is preferable to use less volatile acidic or oxidizing liquids, such as aqueous sulfuric acid solution, sulfuric acid-
A mixed aqueous solution of phosphoric acid, a mixed aqueous solution of sulfuric acid and chromic acid, a phosphoric acid aqueous solution, and the like are preferred from the viewpoint of workability. The thus etched polyacetal resin molded product with excellent surface workability has a peel strength (Kg/cm) of the plating layer of 1 when plated with metal.
Kg/cm or more, usually 1.0 to 2.0 Kg/cm, has a uniform adhesion force to each part of the molded product, and also shows surprising effects when bonding with paints other than metal plating and adhesives. This shows how useful polyacetal resin molded products are. The present invention will be explained in more detail below with reference to Examples. Examples 1 to 11 and Comparative Examples 1 to 4 "Tenatsuku 5010" as polyacetal resin
(Manufactured by Asahi Kasei Corporation, acetal homopolymer,
General grade) 100 parts by weight, 8.7 parts by weight of finely powdered calcium carbonate (Whiten SSB Red, manufactured by Shiraishi Calcium Co., Ltd., average particle size 1.25 microns) and unsaturated polyester (Yupica CLC-
834, manufactured by Toyobo Co., Ltd.) were mixed in a tumbler, and then kneaded in an extruder set at 190°C to form pellets. Using this pellet, an inner handle for an automobile as shown in a perspective view in FIG. 1 was produced by injection molding, and was used as a test material. This inner handle was degreased at 60°C for 2 minutes using an ordinary alkaline degreaser, and after each pre-etching treatment listed in Table 1, 96% sulfuric acid/85% phosphoric acid/water =
Etching was performed by immersing it in a solution consisting of 40/25/35 (weight ratio) at 0°C for 8 minutes. Next, the etched inner handle was plated using a conventional method. First, it is immersed in a pretreatment liquid for plastic plating (manufactured by Okuno Pharmaceutical Co., Ltd., Catalyst) and an accelerator (10% aqueous hydrochloric acid solution) for a predetermined time, and then treated with a chemical plating liquid (manufactured by Okuno Pharmaceutical Co., Ltd., TMP chemical nickel plating liquid). It was chemically plated using a prescribed method and immediately subjected to electroplating. Average plating film thickness is copper 40μ,
Nickel was 10μ and chrome was 0.1μ. The performance of the plated products plated in this manner was as shown in Table 1. The plating performance was measured using the following method. (1) Peeling strength of plated products: Make parallel cuts of 10 mm width on the plated surface, pull the plated film between the cuts in a direction perpendicular to the flat plate surface, and calculate the stress required for peeling.

【table】

[Table] Examples 12 to 14 and Comparative Examples 5 to 7 The same experiment as in Example 2 was carried out by changing the preetching treatment conditions. The results are shown in Table 2.

[Table] *See Figure 1 Examples 15 to 17, Comparative Example 8 An experiment similar to Example 4 was carried out by changing the concentration of 2-pyridineethanol. The results are shown in Table 3.

[Table] *See Figure 1 Examples 18 to 19 and Comparative Example 9 Calcium hydrogen phosphate (average particle size 2 ~3μ) 8.7
Parts by weight, 8.7 parts by weight of barium acetate (average particle size 3μ) and unsaturated polyester (manufactured by Toyobo Co., Ltd., Upica)
0.87 and 0.15 parts by weight of CLC-834) were mixed in a tumbler, and then kneaded in an extruder set at 190°C to form pellets, and the extrusion status was observed. Comparative Example 9 had severe foaming and could not be pelletized. Using this pellet, an inner handle for an automobile as shown in a perspective view in FIG. 1 was made by injection molding, and was used as a test material. The same experiment as in Example 2 was conducted using this inner handle. The results are shown in Table 4.

[Table] *See Figure 1 Examples 20 to 21 and Comparative Example 10 100 parts by weight of polyacetal resin "Tenatsuku 5010" (manufactured by Asahi Kasei Industries, Ltd.) was added with calcium carbonate (manufactured by Shiraishi Calcium Co., Ltd., White In SSB Red). , average particle size
Instead of 8.7 parts by weight of 1.25 μ) and unsaturated polyester, 0.87 parts by weight of polyvinyl acetate and 0.76 parts by weight of ethyl acrylate were mixed in a tumbler, then kneaded in an extruder set at 190°C to pelletize and extrude. I observed the situation. Comparative Example 10 had severe foaming and could not be pelletized. Using this pellet, an inner handle for an automobile as shown in a perspective view in FIG. 1 was produced by injection molding, and was used as a test material. The same experiment as in Example 2 was conducted using this inner handle. The results are shown in Table 5.

[Table] *See Figure 1

[Brief explanation of drawings]

FIG. 1 shows a perspective view of an inner handle for an automobile used in the test. In the figure, A indicates a thick portion on the rib, and B indicates a thin portion other than the rib.

Claims (1)

[Scope of Claims] 1 (a) 100 parts by weight of a polyacetal resin, (b) 0 to 35 parts by weight of a carbonate, phosphate, acetate or a mixture thereof of a group metal of the periodic table, and (c) Polymers, copolymers or mixtures thereof of compounds selected from the group of saturated polyesters, alkyl esters of acrylic acid or methacrylic acid, amides of acrylic acid or methacrylic acid, triallyl cyanurate, diallyl phthalate, vinyl acetate and divinylbenzene. 3-hydroxypyridine, 3-hydroxypyridine,
From 3-pyridinemethanol, 2-pyridinemethanol, 2-pyridineethanol, 4-phenylpyridine, pyridine-4-aldehyde, 2-aminopyridine, nicotinic acid methyl ester, nicotinic acid ethyl ester, isonicotinic acid methyl ester, isoquinoline A method for roughening the surface of a polyacetal resin molded article, which comprises immersing it in a solution containing a selected compound. 2 Pre-treatment of the molded product is performed using 3-hydroxypyridine, 3-pyridinemethanol, 2-pyridinemethanol, 2-pyridineethanol, 4-phenylpyridine, pyridine-4-aldehyde, 2-aminopyridine, nicotinic acid methyl ester, Approximately 3 to 30% of a compound selected from nicotinic acid ethyl ester, isonicotinic acid methyl ester, and isoquinoline
40 in a solution consisting of 25% by weight and about 75-97% by weight of water.
The surface roughening method according to claim 1, which is carried out by immersion at a temperature of ~80°C for 30 seconds to 10 minutes.